اینم کدی که قول داده بودم
int c = 0, maxm = 1;
Console.WriteLine("Kasr ra vared konid :"); //exp 1/2
string r = Console.ReadLine();
string[] k = r.Split(@"/".ToCharArray());
int a = int.Parse(k[0]);
int b = int.Parse(k[1]);
if (a > b)
{
c = a;
}
if (b > a)
{
c = b;
}
for (int i = 1; i <= c; i++)
{
if ((a % i == 0) & (b % i == 0))
{
maxm = i;
}
}
int a2 = a / maxm;
int b2 = b / maxm;
if (b2 == 1)
{
Console.WriteLine(a2);
}
else
{
Console.WriteLine(a2 + @"/" + b2);
}
Console.ReadKey();