代码

#include <cstdio>

int a, b;

int func(int a, int b) {
	return a & b ? func(a ^ b, (a & b) << 1) : a ^ b;
}

int main() {
	scanf("%d %d", &a, &b);
	printf("%d\n", func(a, b));
	return 0;
}

评测结果