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: Time Limit Exceeded)

#include<bits/stdc++.h>
using namespace std;
int main(){
  long long n;
  cin>>n;
  vector<long long> a(n);
  for(int i=0;i<n;i++){
    cin>>a[i];
  }
  int ans=1;
  for(int i=0;i<n;i++){
    for(int j=i+1;j<n;j++){
      if(a[i]==a[j]){
        ans--;
      }
    }
    if(ans==0){
      break;
    }
  }
  if(ans){
    cout<<"YES"<<endl;
  }
  else{
    cout<<"NO"<<endl;
  }
}