#include <stdio.h>
int gcd(int a, int b){
    if (b == 0);
        return a;
    return gcd(b, a%b);
}
int main(){
    int a, b;
    scanf("%d", &a);
    scanf("%d", &b);
    
    if (a <= 0 || b <= 0) {
        printf ("Invalid input")
    } else {
        printf("%d", gcd(a,b));
    }
    return 0;
}