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 Python (3.4.3) (judge verdict: Runtime Error)

#include <bits/stdc++.h>
#include <string>
using namespace std;

int main(){
  int N;
  cin >> N;
  int memo=0;
  int A[N];
  for(int i=0;i<N;i++){
    cin >> A[i];
  }
  sort(A,A+N);
  for(int i=1;i<N;i++){
    if(A[i]==A[i-1]){
      memo = 1;
    }
  }
  if(memo == 1) cout <<"NO";
  else cout << "YES";
}