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()
{
    long N, ap;
    int temp;
    string result = "YES";
    vector<long long> lst;
    cin >> N;
    for (int i = 0; i < N; i++)
    {
        cin >> ap;
        lst.push_back(ap);
    }

    sort(lst.begin(), lst.end());
    temp = lst.size();
    lst.erase(unique(lst.begin(), lst.end()), lst.end());

    if (temp != lst.size())
        result = "NO";

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