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;

int main(){
    int n, k;
    cin >> n >> k;
    int tmp, ans;
    int *p = new int[n];
    long long smallSum = 0, bigSum = 0;
    for(int i = 0; i < k; i++){
        scanf("%d", &p[i]);
        bigSum += p[i];
    }
    ans = bigSum;
    for(int i = k; i < n; i++){
        scanf("%d", &p[i]);
        bigSum += p[i];
        smallSum += p[i - k];
        tmp = bigSum - smallSum;
        if(tmp > ans) ans = tmp;
    }
    cout << (double)(ans + k) / 2.0 << endl;
    return 0;
}