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;
long long a[200005];
int main ()
{
    ///without test case
    long long int b,c,d,t,n,i,j;
     set<int>s;
    cin >>n;
    for(i=0;i<n;i++)
    {
       cin>>a[i];
       s.insert(a[i]);
    }
    b=s.size();
    if(b<n)
    {
        cout<< "NO"<<"\n";
    }
    else
    {
        cout << "YES"<<"\n";
    }

}