C# Online Compiler | .NET Fiddle

using System;

public class Program
{
	public static void Main()
	{
		int i, cal, suma_alumno, num_alumnos;
		double promedio_alumno, promedio_grupo, suma_grupo;
		string resp;
		suma_grupo = 0;
		num_alumnos = 1;
		do
		{
			suma_alumno = 0;
			for (i = 1; i <= 5; i++)
			{
				Console.WriteLine("Dame la calificación " + i + " del alumno número " + num_alumnos);
				cal = Convert.ToInt32(Console.ReadLine());
				suma_alumno = suma_alumno + cal;
			}

			promedio_alumno = suma_alumno / 5;
			Console.WriteLine("El promedio del alumno número " + num_alumnos + " es de: " + promedio_alumno);
			suma_grupo = suma_grupo + promedio_alumno;
			Console.WriteLine("¿Deseas capturar las calificaciones de otro alumno? S/N");
			resp = Console.ReadLine();
			if (resp == "S" || resp == "s")
				num_alumnos++;
		}
		while (resp == "S" || resp == "s");
		promedio_grupo = suma_grupo / num_alumnos;
		Console.WriteLine("El promedio general del grupo de " + num_alumnos + " alumnos es de: " + promedio_grupo);
	}
}

 
using System;
​
public class Program
{
    public static void Main()
    {
        int i, cal, suma_alumno, num_alumnos;
        double promedio_alumno, promedio_grupo, suma_grupo;
        string resp;
        suma_grupo = 0;
        num_alumnos = 1;
        do
        {
            suma_alumno = 0;
            for (i = 1; i <= 5; i++)
            {
                Console.WriteLine("Dame la calificación " + i + " del alumno número " + num_alumnos);
                cal = Convert.ToInt32(Console.ReadLine());
                suma_alumno = suma_alumno + cal;
            }
​
            promedio_alumno = suma_alumno / 5;
            Console.WriteLine("El promedio del alumno número " + num_alumnos + " es de: " + promedio_alumno);
            suma_grupo = suma_grupo + promedio_alumno;
            Console.WriteLine("¿Deseas capturar las calificaciones de otro alumno? S/N");
            resp = Console.ReadLine();
            if (resp == "S" || resp == "s")
                num_alumnos++;
        }
        while (resp == "S" || resp == "s");
        promedio_grupo = suma_grupo / num_alumnos;
        Console.WriteLine("El promedio general del grupo de " + num_alumnos + " alumnos es de: " + promedio_grupo);
    }
}

: Compilation error (line 0, col 0): Metadata file 'c:\LocalResources\NuGet\Packages\BouncyCastle\1.8.2.0\lib\BouncyCastle.Crypto.dll' could not be found
: Compilation error (line 0, col 0): Metadata file 'c:\LocalResources\NuGet\Packages\Nethereum.Signer\4.28.0.0\lib\net461\Nethereum.Signer.dll' could not be found
: Compilation error (line 0, col 0): Metadata file 'c:\LocalResources\NuGet\Packages\Nethereum.RPC\4.28.0.0\lib\net461\Nethereum.RPC.dll' could not be found
: Compilation error (line 0, col 0): Metadata file 'c:\LocalResources\NuGet\Packages\Nethereum.Model\4.29.0.0\lib\net461\Nethereum.Model.dll' could not be found
: Compilation error (line 0, col 0): Metadata file 'c:\LocalResources\NuGet\Packages\Nethereum.Util\4.29.0.0\lib\net461\Nethereum.Util.dll' could not be found
: Compilation error (line 0, col 0): Metadata file 'c:\LocalResources\NuGet\Packages\Nethereum.Hex\4.29.0.0\lib\net461\Nethereum.Hex.dll' could not be found
: Compilation error (line 0, col 0): Metadata file 'c:\LocalResources\NuGet\Packages\Nethereum.RLP\4.29.0.0\lib\net461\Nethereum.RLP.dll' could not be found
: Compilation error (line 0, col 0): Metadata file 'c:\LocalResources\NuGet\Packages\Nethereum.Signer\4.29.0.0\lib\net461\Nethereum.Signer.dll' could not be found
: Compilation error (line 0, col 0): Metadata file 'c:\LocalResources\NuGet\Packages\BouncyCastle\1.8.2.0\lib\BouncyCastle.Crypto.dll' could not be found
: Compilation error (line 0, col 0): Metadata file 'c:\LocalResources\NuGet\Packages\Nethereum.Model\4.29.0.0\lib\net461\Nethereum.Model.dll' could not be found
: Compilation error (line 0, col 0): Metadata file 'c:\LocalResources\NuGet\Packages\Nethereum.Util\4.29.0.0\lib\net461\Nethereum.Util.dll' could not be found
: Compilation error (line 0, col 0): Metadata file 'c:\LocalResources\NuGet\Packages\Nethereum.Hex\4.29.0.0\lib\net461\Nethereum.Hex.dll' could not be found
: Compilation error (line 0, col 0): Metadata file 'c:\LocalResources\NuGet\Packages\Nethereum.RLP\4.29.0.0\lib\net461\Nethereum.RLP.dll' could not be found
: Compilation error (line 0, col 0): Metadata file 'c:\LocalResources\NuGet\Packages\Nethereum.JsonRpc.RpcClient\4.29.0.0\lib\net461\Nethereum.JsonRpc.RpcClient.dll' could not be found
: Compilation error (line 0, col 0): Metadata file 'c:\LocalResources\NuGet\Packages\Nethereum.ABI\4.29.0.0\lib\net461\Nethereum.ABI.dll' could not be found
: Compilation error (line 0, col 0): Metadata file 'c:\LocalResources\NuGet\Packages\Nethereum.Accounts\4.29.0.0\lib\net461\Nethereum.Accounts.dll' could not be found
: Compilation error (line 0, col 0): Metadata file 'c:\LocalResources\NuGet\Packages\Nethereum.Contracts\4.29.0.0\lib\net461\Nethereum.Contracts.dll' could not be found
: Compilation error (line 0, col 0): Metadata file 'c:\LocalResources\NuGet\Packages\Nethereum.Web3\4.29.0.0\lib\net461\Nethereum.Web3.dll' could not be found
: Compilation error (line 0, col 0): Metadata file 'c:\LocalResources\NuGet\Packages\Nethereum.Util\4.29.0.0\lib\net461\Nethereum.Util.dll' could not be found
: Compilation error (line 0, col 0): Metadata file 'c:\LocalResources\NuGet\Packages\Nethereum.Hex\4.29.0.0\lib\net461\Nethereum.Hex.dll' could not be found
: Compilation error (line 0, col 0): Metadata file 'c:\LocalResources\NuGet\Packages\Nethereum.Signer\4.29.0.0\lib\net461\Nethereum.Signer.dll' could not be found
: Compilation error (line 0, col 0): Metadata file 'c:\LocalResources\NuGet\Packages\Nethereum.Model\4.29.0.0\lib\net461\Nethereum.Model.dll' could not be found
: Compilation error (line 0, col 0): Metadata file 'c:\LocalResources\NuGet\Packages\Nethereum.Util\4.29.0.0\lib\net461\Nethereum.Util.dll' could not be found
: Compilation error (line 0, col 0): Metadata file 'c:\LocalResources\NuGet\Packages\Nethereum.Hex\4.29.0.0\lib\net461\Nethereum.Hex.dll' could not be found
: Compilation error (line 0, col 0): Metadata file 'c:\LocalResources\NuGet\Packages\Nethereum.RLP\4.29.0.0\lib\net461\Nethereum.RLP.dll' could not be found
: Compilation error (line 0, col 0): Metadata file 'c:\LocalResources\NuGet\Packages\Nethereum.JsonRpc.RpcClient\4.29.0.0\lib\net461\Nethereum.JsonRpc.RpcClient.dll' could not be found
: Compilation error (line 0, col 0): Metadata file 'c:\LocalResources\NuGet\Packages\Nethereum.BlockchainProcessing\4.29.0.0\lib\net461\Nethereum.BlockchainProcessing.dll' could not be found
: Compilation error (line 0, col 0): Metadata file 'c:\LocalResources\NuGet\Packages\Nethereum.ABI\4.29.0.0\lib\net461\Nethereum.ABI.dll' could not be found
: Compilation error (line 0, col 0): Metadata file 'c:\LocalResources\NuGet\Packages\Nethereum.Accounts\4.29.0.0\lib\net461\Nethereum.Accounts.dll' could not be found
: Compilation error (line 0, col 0): Metadata file 'c:\LocalResources\NuGet\Packages\Nethereum.KeyStore\4.29.0.0\lib\net461\Nethereum.KeyStore.dll' could not be found
: Compilation error (line 0, col 0): Metadata file 'c:\LocalResources\NuGet\Packages\Nethereum.RPC\4.29.0.0\lib\net461\Nethereum.RPC.dll' could not be found
: Compilation error (line 0, col 0): Metadata file 'c:\LocalResources\NuGet\Packages\Nethereum.Contracts\4.29.0.0\lib\net461\Nethereum.Contracts.dll' could not be found