#include <stdio.h>

int main() {
    int n, m;
    
    if (scanf("%d %d", &n, &m) != 2) {
        printf("Invalid input");
        return 0;
    }
    
    if (n < 0 || m < 0) {
        printf("Invalid input");
        return 0;
    }
    
    int a = n, b = m;
    while (b != 0) {
        int temp = b;
        b = a&b;
        a = temp;
    }
    
    printf("%d", a);
    
    return 0;
}