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 <vector>
#include <iostream>
#include <string>
using namespace std;
 
 
int main(){
  int N;
  cin >> N;
  vector<int> A(N);
  for (int i=0; i<N; i++){
    cin >> A[i];
  }
  string x="YES";
    for (int i=0; i<N; i++){
      for (int j=0;j<i; j++){
        if (A[i]==A[j]){
          x="NO";
          break;
        }
      }
    }
 
  
  cout << x << endl;
  return 0;
}