#include "coins.h"
#include <bits/stdc++.h>
using namespace std;
#define debug(v) cerr<<#v" = "<<(v)<<"\n"
using ll=long long;
using ull=unsigned long long;
using pll=pair<ll,ll>;
using vll=vector<ll>;
using vpll=vector<pll>;
using vvll=vector<vll>;
const ll INF=1e9+100;
const ll MOD=998244353;
const ll MAXN=2e5+100;
vector<int> coin_flips(vector<int> b, int c){
for(int i=0; i<b.size(); i++) if(b[i]) c^=i;
vector<int> ans={c};
return ans;
}
int find_coin(vector<int> b){
int c=0;
for(int i=0; i<b.size(); i++) if(b[i]) c^=i;
return c;
}
