#include <cstdio>
#include <iostream>
#include <vector>
#include <list>
#include <string>
#include <set>
#include <map>
#include <algorithm>
#include <fstream>
#include <cmath>
#include <queue>
#include <stack>
#include <cassert>
#include <cstring>
#include <climits>
#include <functional>
#include <cstdlib>
#include <complex>
#include <array>
#include <iomanip>
#include <bitset>
#define fileIO(name) if(fopen(name".in", "r")) {freopen(name".in", "r", stdin); freopen(name".out", "w", stdout);}
using namespace std;
const int MAXN = 3e4 + 111;
using ll = long long;
const int P = 31;
const ll mod1 = 1e9 + 7;
const ll mod2 = 998244353;
using ld = long double;
const ld EPS = 1e-5;
using pii = pair<int, int>;
const int K = 300;
vector<int> coin_flips(vector<int> b, int c)
{
vector<int> flips(1);
int res = 0;
for (int i = 0; i < 64; i++)
res ^= (i * b[i]);
res = res ^ c;
flips[0] = res;
return flips;
}
int find_coin(vector<int> b)
{
int xr = 0;
for (int i = 0; i < 64; i++)
xr ^= (b[i] * i);
return xr;
}
