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 (GCC 5.4.1) (judge verdict: Runtime Error)

#include <stdio.h>
#include <stdlib.h>

int k[100000000];

int main()
{
    int i,f=1,n;
    long a[200000]={0};
    scanf("%d",&n);
    for(i=0;i<n;i++)
    {
        scanf("%ld",&a[i]);
        if(f == 1)
            k[a[i]]++;
        if(k[a[i]] > 1)
            f = 0;
    }
    if(f)
        printf("Yes");
    else
        printf("No");
    return 0;
}