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>
#include<string.h>

int main(void){
    int n,count=0;
    int a[n];

    scanf("%d",&n);
    for(int i=0;i<n;i++)
        scanf("%d",&a[i]);


    for(int k=0;k<n;k++){
        for(int j=0;j<n;j++){
            if(a[k] == a[j]){
                count ++;
                break;
            }
        }
        if(count !=0) break;
    }

    if(count==1){
      printf("YES");
    }else if(count==0){
        printf("NO");
    }
    return 0;
}