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 <iostream>
#include<vector>
#include<algorithm>
using namespace std;

int main() {
    int n; cin>>n;
    bool ok=false;
    vector <int> v(n);
    for(int i=0; i<n; i++){
        cin>>v[i];
    }
    sort(v.begin(), v.end());
    for(int i=0; i<n; i++){
            if(v[i]==v[i+1]){cout<<"NO"; ok=true; break;}
    }
    if(ok==false)cout<<"YES";
}