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>

#define Bye return 0
#define ll long long

using namespace std;

void solve(){
    int n; cin>>n;
    
    map<int, int> a;
    for (int i=0; i<n; i++){
        int e; cin>>e;
        a[e]++;
    }

    for (auto i : a){
        if(i.second == 2){
            cout<<"NO"<<endl;
            return;
        }
    }
    
    cout<<"YES"<<endl;
}

int main(){
    solve();
    Bye;
}