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: Runtime Error)

#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define all(v) v.begin(),v.end()
#define rall(v) v.rbegin(),v.rend()
typedef long long ll;
#define _GLIBCXX_DEBUG
int main()	{
  int n;
  cin>>n;
  vector<int>a(n);
  rep(i,n) cin>>a[i];
  vector<int>d(1000000010);
  rep(i,1000000001){
    d[a[i]]++;
  }
  rep(i,n){
    if(d[i]>=2){
      cout<<"NO"<<endl;
      return 0;
    }
  }
  cout<<"YES"<<endl;
}