Pile

input/code.cpp: In function 'int main()':
input/code.cpp:26:7: warning: unused variable 'g' [-Wunused-variable]
  bool g[101010] = {0};
       ^

#include <bits/stdc++.h>

#define i64 long long
#define u64 unsigned long long
#define i32 int
#define u32 unsigned int

#define pii pair<int, int>
#define pll pair<long long, long long>

#define ld long double
#define defmod 1000000007

#define mati64(a,b) vector<vector<i64>>(a, vector<i64>(b, 0));
using namespace std;


int main(){
	cin.sync_with_stdio(0);
	cin.tie(0);
	
	int n; cin >> n;
	int a[101010];
	for(int i = 0; i < n; ++i)
		cin >> a[i];
	bool g[101010] = {0};
	stack<int> lol;
	int j = 0;
	for(int i = 1; i <= n; ++i){
		lol.push(i);
		while(j < n && lol.size() > 0 &&  a[j] == lol.top()){
			lol.pop();
			j++;
		}
	}
	if(lol.size() == 0)
		cout << "Not a proof" << endl;
	else
		cout << "Cheater" << endl;
	return 0;
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED

Test 14

Verdict: ACCEPTED

Test 15

Verdict: ACCEPTED

Test 16

Verdict: ACCEPTED

Test 17

Verdict: ACCEPTED

Test 18

Verdict: ACCEPTED

Test 19

Verdict: ACCEPTED

Test 20

Verdict: ACCEPTED

Test 21

Verdict: ACCEPTED

Test 22

Verdict: ACCEPTED

Test 23

Verdict: ACCEPTED

Test 24

Verdict: ACCEPTED

Test 25

Verdict: ACCEPTED

Test 26

Verdict: ACCEPTED

Test 27

Verdict: ACCEPTED

Test 28

Verdict: ACCEPTED

Test 29

Verdict: ACCEPTED

Test 30

Verdict: ACCEPTED