Submission #2372666

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Source Code Expand

#include "bits/stdc++.h"
#define in std::cin
#define out std::cout
#define rep(i,N) for(int i=0;i<N;++i)
typedef long long int LL;

LL N, x, ans;

int main()
{
	in >> N;
	std::vector<LL>a(N);
	std::vector<bool>flag(N);
	rep(i, N) in >> a[i];
	std::sort(a.begin(), a.end(), std::greater<LL>());
	rep(i, N) x ^= a[i];
	for (LL k = 32; k >= 0; --k)
	{
		while (x & (1LL << k) && ans < N)
		{
			rep(i, N)
			{
				if (!flag[i] && (a[i] & (1LL << k)))
				{
					--a[i];
					++ans;
					flag[i] = true;
					break;
				}
			}
			x = 0;
			rep(i, N) x ^= a[i];
		}
	}
	out << (x == 0 ? ans : -1) << std::endl;
	return 0;
}

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