#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 %d",&a,&b);
    if(a==0&&b==0){
        printf("Invalid input");
        return 0;
        
    }
    if(a<0)a=-a;
    if(b<0)b=-b;{
    
    printf("%d",gcd(a,b));
    return 0;
}