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;
    cin >> n;
    bool ans = true;
    map <int, int> m;
    int a[n];
    for(int i = 0; i < n; i++)
    {
        cin >> a[i];
        m[a[i]]++;
        if(m[a[i]] > 1)
        {
            ans = false;
        }
    }
    if(ans)
    {
        cout << "YES";
    }
    else
    {
        cout << "NO";
    }
    return 0;
}