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: Wrong Answer)

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

int compare(const void *a, const void *b)
{
    int num1= *(int *)a;
    int num2= *(int *)b;
    
    if(num1<num2)
        return -1;
    if(num1>num2)
        return 1;
    
    return 0;
}
int main()
{
    int i, na;
    int a[210000];
    
    printf("\n");
    if(scanf("%d", &na)==1)
    {
        for(i=1; i<na+1; i++)
        {
            printf("\n");
            scanf("%d", &a[i]);

        }
        qsort(a, sizeof(a) / sizeof(int), sizeof(int), compare);
        
        for(int i=1; i<na; i++){
            for(int j=na; j>na-i-1; j--){
                if(a[i]==a[j])
                    {
                        printf("NO");
                        return (0);
                    }
                }
            }
           printf("YES");
            return (0);
    }
}