#include<stdio.h>

int gcd(int a, int b){
    if(b==0)
    return 0;
    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;
    }
}