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 <bits/stdc++.h>
 
using namespace std;
 
#define ll long long
#define IOS ios_base :: sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define endl "\n"

int main()
{
	map<int,int>mp;
	int n;
	cin>>n;
	for(int i = 1; i <= n; i++)
	{
		int a;
		cin >> a;
		mp[a]++;
	}
	for(auto it : mp)
	{
		if(it.second > 1) 
		{
			cout<< "NO\n";
			return 0;
		}
	}
	cout << "YES\n";
	return 0;
}