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 9.2.1) (judge verdict: Accepted)

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

int compare(const void* a,const void* b);

int main(void)
{
    int n=0,flag=1;
    long int array[200000]={};
    scanf("%d",&n);
    for(int i=0;i<n;i++){
        scanf("%ld",&array[i]);
    }
    qsort(array,n,sizeof(long int),compare);
    for(int i=0;i<n-1;i++){
        if(array[i]==array[i+1]){
            flag=0;
            break;
        }
    }
    if(flag==1){
        printf("YES");
    } else {
        printf("NO");
    }
    return 0;
}

int compare(const void* a,const void* b){
    long *A=(long*)a;
    long *B=(long*)b;
    if(*A-*B<0) return -1;
    if(*A-*B>0) return 1;
    return 0;
}