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 (Clang 3.8.0) (judge verdict: Wrong Answer)

#include <stdio.h>

int main()
{
    int N, flag = 0, i, j;

    scanf("%d", &N);

    int arr[N];

    for(i = 0; i < N; i++)
        scanf("%d", &arr[i]);

    for(i = 0; i < N; i++)
    {
        for(j = i + 1; j < N; j++)
        {
            if(arr[i] == arr[j])
            {
            flag = 1;
            break;
            }
        }
    }

    if(flag == 1)
        printf("\nNO\n");
    else if(flag == 0)
        printf("\nYes\n");
}