#include<stdio.h>
int main(){
    inbt a,b;
    if(scanf("%d %d",&2,&b)!=2){
        printf("Invalid input");
        return 0;
    }
    if(a<0)a=-a;
    if(b<0)b=-b;
    while(b !=0){
        int temp=b;
        b=a%b;
        a=temp;
    }
    printf("%d",a);
    return 0;
}