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++ (GCC 9.2.1) (judge verdict: Accepted)

#include<bits/stdc++.h>
using namespace std;
int main()
{
    ios_base::sync_with_stdio(false); 
    cin.tie(NULL);  
    int t;
    //cin>>t;
    //while(t--)
    {
        int n ;
        cin>>n;
        vector <int> arr(n);
        for(int i = 0;i<n;i++)
        {
            cin>>arr[i];
        }
        set <int> check;
        check.insert(arr.begin(),arr.end());
        if(check.size()==n)
        cout<<"YES\n";
        else{
            cout<<"NO\n";
        }
    }
    return 0;
}