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 rep(i, n)	for(int i=0;i<(int)(n);i++)
using namespace std;
using ll=long long;

int main(){
    int n;
    cin>>n;
    vector<int> a(n);
    rep(i,n) cin>>a[i];
    sort(a.begin(),a.end());

    rep(i,n-1){
        if(a[i]==a[i+1]){
            cout<<"NO"<<endl;
            return 0;
        }
    }
    cout<<"YES"<<endl;
}