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: Accepted)

#include <bits/stdc++.h>

using namespace std;
typedef long long ll;

int main() {
    int n;
    cin >> n;
    vector <ll> A(n);
    for (int i = 0; i < n; i++){
        ll a;
        cin >> a;
        A[i] = a;
    }
    
    sort(A.begin(), A.end());
    
    for(int j = 0; j < n-1; j++){
//        cout << A[j] << ":" << A[j+1] << endl;
        if(A[j] == A[j+1]){
            cout << "NO" << endl;
            return 0;
        }
        
    }
    
    cout << "YES" << endl;
    
}