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: Runtime Error)

#include <bits/stdc++.h>
#define rep(i,n) for(int i=0; i<(n); ++i)
using namespace std;
using ll = long long;
using P = pair<int, int>;

int main(){
    int n;
    cin >> n;

    vector<int> a(n);
    rep(i,n){
        cin >> a.at(i);
    }
    sort(a.begin(),a.end());

    bool sta = false;
    for(int i=0; i<n; i++){
        if(a.at(i)==a.at(i+1)){
            cout << "NO" << endl;
            sta = true;
            break;
        }
    }

    if(!sta){
        cout << "YES" << endl;
    }

    return 0;
}