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(){
    int *a=(int*)malloc(sizeof(int)*1000000000);
    for(int i=0;i<1000000000;i++){
        a[i]=0;
    }
    int n;
    int flag=0;
    scanf("%d",&n);
    for(int i=0;i<n;i++){
        int b;
        scanf("%d",&b);
        if(a[b]==1){
            printf("NO");
            flag=1;
            break;
        }else{
            a[b]=1;
        }
    }
    if(flag==0){
        printf("YES");
    }
    return 0;
}