#include <cstdio>

using namespace std;

int adun(int a, int b)
{
    while(a & b)
    {
        int r = (a & b) << 1;
        b ^= a;
        a = r;
    }
    return a ^ b;
}

int main()
{
    int a, b;
    freopen("adunare.in", "r", stdin);
    freopen("adunare.out", "w", stdout);
    scanf("%d%d", &a, &b);
    printf("%d", adun(a, b));
    return 0;
}