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 <set>

using namespace std;



int N;
vector<int> A;




int main()
{

	bool ans = true;
	cin >> N;

	A = vector<int>(N);
	set<int> s;

	for (int i = 0; i < N; i++) {
		cin >> A[i];

		decltype(s)::iterator it = s.find(A[i]);
		if (it == s.end()) {
			s.insert(A[i]);
		}
		else {
			ans = false;
			break;
		}
	}

	

	cout << (ans?"YES":"NO") << endl;

	return 0;
}