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>

int main(){
    int i = 0,j=0;
    int n,a,b;
    int A[n+1];
    int flag = 0;

    scanf("%d",&n);
    for(i = 0 ; i < n-1 ; i++){
        scanf("%d",&A[i]);
    }
    
    for(i = 0; i < n-1 ; i++){
        for(j = i+1 ; j < n ; j++){
            if(A[i] == A[j]){
                printf("NO\n");
                flag = 2;
                break;
            }
            flag = 1;
        }
        if(flag == 2){
            break;
        }
    }
    if(flag == 1){
        printf("YES\n");
    }
}