#include <algorithm>
#include <bitset>
#include <cassert>
#include <chrono>
#include <complex>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <deque>
#include <functional>
#include <iomanip>
#include <iostream>
#include <iterator>
#include <limits>
#include <list>
#include <map>
#include <numeric>
#include <queue>
#include <random>
#include <ratio>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>
#include <climits>
#include<coins.h>
// #define ll long long
#define ld long double
#define mp make_pair
#define pb push_back
#define in insert
#define vll vector<ll>
#define endl "\n"
#define pll pair<ll,ll>
#define f first
#define s second
#define FOR(i,a,b) for(int i=(a),_b=(b); i<=_b; i++)
// #define int ll
#define sz(x) (ll)x.size()
#define all(x) (x.begin(),x.end())
using namespace std;
// const ll INF = 1e12;
// const ll N =(1e5+5); // TODO : change value as per problem
// const ll MOD = 1e9;
std::vector<int> coin_flips(std::vector<int> b, int c) {
int x = 0;
for(int i = 0;i<64;i++){
x ^= b[i];
}
if(x == 0) {
// even number of 1s
vector<int> v;
v.pb(c);
return v;
}
else{
// odd number of 1s
vector<int> v;
v.pb(c ^ x);
return v;
}
}
int find_coin(std::vector<int> b) {
int x =0;
for(int i =0;i<64;i++)
x ^= b[i];
return x;
}
