using System;
public class Program
{
public static void Main()
Console.WriteLine("Saisissez deux nombres a et b");
int a=Convert.ToInt32(Console.ReadLine());
int b=Convert.ToInt32(Console.ReadLine());
int c=a%b;
while(c >0)
a=b;
b=c;
c= a%b;
}
Console.WriteLine(b);