public static void Main(string[] args)
Console.WriteLine("Enter first String");
string s=Console.ReadLine();
Console.WriteLine("Enter second String");
string s2=Console.ReadLine();
string b=UserProgramCode.stringad(s,s2);
Console.WriteLine("invalid");
public static string stringad(string str,string str2)
char[] ia = str2.ToCharArray();
string new_ia=new string(ia);
if(((int)str[i]> 57 && (int)str[i]<65)||((int)str[i]>32 && (int)str[i]<48))
string op= str.Insert(len/2,new_ia);