def gcd(x,y):
    if x>y:
        if (x%y)== 0:
            return y
        else:
            r = x%y
            gcd(y,r)

    elif y>x:
        if (y%x)==0:
            return x
        else:
            r = y%x
            gcd(x,r)


    else:
        return x
print gcd(4,6)