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 <bits/stdc++.h>
using namespace std;
int main() {
int N;
cin>>N;
vector<int> A(N);
for (int i = 0; i < N; i++) {
  cin >> A.at(i);
}
for (int i = 0; i < N; i++) {
    for (int j = 0; j < N; j++) {
        if(i!=j){
            if(A[i]==A[j]){
                cout<<"NO"<<endl;
                return 0;
            }
        }
    }
}
cout<<"YES"<<endl;
}
//はじめてのABCさんかん