Mikasa #735-div2

int main() {
    int _ = read;
    while (_--) {
        int n = read, m = read;
        if(n > m) {
          puts("0");
          continue;
        }
        ++m;
        int ans = 0;
        for (int i = 30; i >= 0; i--) {
            if ((m & (1 << i)) && !(n & (1 << i))) ans |= 1 << i;
            else if ((n & (1 << i)) && !(m & (1 << i))) break;
        }
        printf("%d\n", ans);
    }
    return 0;
}