int Gcd(int a, int b);
int main()
{
int a, b, c;
scanf("%d %d", &a, &b);
c = Gcd(a, b);
if (c != -1)
{
printf("%d\n", c);
}
else
{
printf("Input number should be positive!\n");
}
return 0;
}int Gcd(int a, int b)
{
if (a <= 0 || b <= 0)
{
return -1;
}
else if (a > b)
{
Gcd(a - b, b);
}
else if (a < b)
{
Gcd(a, b - a);
}
else if (a == b)
{
return a;
}
}