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: Accepted)

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

int main(void){
    static char A[1000000010];
    int  N;
    int num;
    int ans;

    scanf("%d",&N);

    for(int i=0;i<1000000010;i++){
        A[i]=0;
    }

    for(int i=0;i<N;i++){
        scanf("%d",&num);
        A[num]++;
        if(A[num]>1){
            printf("NO");
            return 0;
        }
    }

    printf("YES");

    return 0;
}