public static void Main()
Console.WriteLine("Ingrese primer nota parcial: ");
double N1 = Convert.ToDouble(Console.ReadLine());
Console.WriteLine("Ingrese segunda nota parcial: ");
double N2 = Convert.ToDouble(Console.ReadLine());
Console.WriteLine("Ingrese tercera nota parcial: ");
double N3 = Convert.ToDouble(Console.ReadLine());
double P = (N1 + N2 + N3) /3;
Console.WriteLine("El promedio es: {0}", P);