Problem:
Score : 300 points

Problem Statement

Given is a sequence of integers A_1, A_2, ..., A_N.
If its elements are pairwise distinct, print YES; otherwise, print NO.

Constraints

2 ≤ N ≤ 200000

1 ≤ A_i ≤ 10^9

All values in input are integers.

Input

Input is given from Standard Input in the following format:

N
A_1 ... A_N

Output

If the elements of the sequence are pairwise distinct, print YES; otherwise, print NO.

Sample Input 1

5
2 6 1 4 5

Sample Output 1

YES

The elements are pairwise distinct.

Sample Input 2

6
4 1 3 1 6 2

Sample Output 2

NO

The second and fourth elements are identical.

Sample Input 3

2
10000000 10000000

Sample Output 3

NO

Solution in C++14 (GCC 5.4.1) (judge verdict: Time Limit Exceeded)

#include <iostream>
#include <stdio.h>
#include <vector>
#include <algorithm>

using namespace std;

int main(){
  long long n, temp;
  vector<long long> v;
  string res = "YES";
  cin >> n;

  for(int i = 0; i < n; i++) {
    cin >> temp;
    int j;
    for(j = 0; j < v.size(); j++){
      //cout << v[j] << " ";
      if(v[j] == temp){
        res = "NO";
        break;
      }
    }
    if(j == v.size()){
        v.push_back(temp);
    }else{
      break;
    }
  }

  cout << res << endl;

  return 0;
}