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: Wrong Answer)

/**
 * Title: C - Distinct or Not
 * Url: https://atcoder.jp/contests/abc154/tasks/abc154_c
 */
#include<iostream>
#include<string>
#include<vector>
#include<algorithm>
#include<cmath>
#include<map>
#include<set>
#include<numeric>
#include<functional>
#include<sstream>
#include<iomanip>

using namespace std;

#define ll long long

int main() {
    int n;
    cin >> n;
    vector<ll> a(n);
    for(int i=0; i<n; i++) cin >> a[i];
    sort(a.begin(), a.end());
    bool flag = true;
    for(int i=1; i<n; i++) {
        if(a[i]==a[i-1]) flag = false; break;
    }
    if(flag) {
        cout << "YES" << endl;
    } else {
        cout << "NO" << endl;
    }

    return 0;
}