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;


int main() {

    int N;
    long long int X;

    cin >> N;

    vector<long long int> A(N);

    for (int i = 0; i < N; i++) {
        cin >> A.at(i);
    }

    std::sort(A.begin(), A.end());
    A.erase(std::unique(A.begin(), A.end()), A.end());

    string result = "YES";

    if (N != A.size()) result = "NO";

    
    cout << result << endl;
    
    return 0;
}