# ZeroJudge - c489: kevin 的啃得雞
### 題目連結：https://zerojudge.tw/ShowProblem?problemid=c489
###### tags: `ZeroJudge` `位元運算`

#include <stdio.h>
using namespace std;

int main() {
	int bitsSum[32] = {}, numbers[2], counts[2] = {}, amount, buffer, pointer = 0, maximum, answer = 0, i;
	scanf("%d", &amount);
	while (amount--) {
		scanf("%d", &buffer);
		for (i = 0; i < pointer; ++i)
			if (numbers[i] == buffer)
				++counts[i];
		if (pointer < 2) {
			for (i = 0; i < pointer; ++i)
				if (numbers[i] == buffer)
					break;
			if (i == pointer)
				numbers[pointer] = buffer, ++counts[pointer], ++pointer;
		}
		for (int i = 0; i < 32; ++i)
			if (buffer & (1 << i))
				++bitsSum[i];
	}
	maximum = (counts[0] >= counts[1] ? counts[0] : counts[1]);
	for (int i = 0; i < 32; ++i)
		if (bitsSum[i] % maximum)
			answer += (1 << i);
	printf("%d\n", answer);
}