| # | Time | Username | Problem | Language | Result | Execution time | Memory | 
|---|---|---|---|---|---|---|---|
| 1211177 | PlayVoltz | 세 명의 친구들 (BOI14_friends) | C11 | 0 ms | 0 KiB | 
#include <cstdio>
#include <stdio.h>
#include <stdbool.h>
#include <iostream>
#include <map>
#include <vector>
#include <climits>
#include <stack>
#include <string>
#include <queue>
#include <algorithm>
#include <set>
#include <unordered_set>
#include <unordered_map>
#include <cmath>
#include <cctype>
#include <bitset>
#include <iomanip>
#include <cstring>
#include <numeric>
#include <cassert>
#include <chrono>
using namespace std;
#define int long long
#define pii pair<int, int>
#define mp make_pair
#define pb push_back
#define fi first
#define se second
int32_t main(){
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	int n;
	string s, a, b;
	bool cana=1, canb=1, flaga=0, flagb=0;
	cin>>n>>s;
	if (!(n%2)){
		cout<<"NOT POSSIBLE";
		return 0;
	}
	for (int i=0; i<n/2; ++i)a+=s[i];
	for (int i=n/2+1; i<n; ++i)b+=s[i];
	for (int i=0, p=0; i<n/2+1; ++i){
		if (s[i]==b[p])++p;
		else if (!flaga)flaga=1;
		else cana=0;
	}
	for (int i=n/2, p=0; i<n; ++i){
		if (s[i]==a[p])++p;
		else if (!flagb)flagb=1;
		else canb=0;
	}
	if (!cana&&!canb)cout<<"NOT POSSIBLE";
	else if (!cana)cout<<a;
	else if (!canb)cout<<b;
	else if (a==b)cout<<a;
	else cout<<"NOT UNIQUE";
}
