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>

#define ll long long

using namespace std;

map<ll, bool>mp;

int main()
{
    bool f = false;
    int n;
    cin >> n;
    ll arr[n];
    cin >> arr[0];
    mp[ arr[0] ] = true;
    for(int i = 1; i < n; i++)
    {
        cin >> arr[i];
        if( mp[ arr[i] ] )
            f = true;
        mp [ arr[i] ] = true;
    }
    if( f )
        cout << "NO" << endl;
    else cout << "YES" << endl;

   return 0;

}