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>
#include <string.h>
#define ll long long
#define fr(i,n,m) for(ll i=n;i<m;i++)
int com(const void *a,const void *b) {
    return *(int*)a-*(int*)b;
}
int main()
{
    ll n,cen=0;
    scanf("%lli",&n);
    ll num[n];
    fr(i,0,n) {
        scanf("%lli",&num[i]);   
    }
    qsort(num,n,sizeof(ll),com);
    fr(i,0,n-1) {
        if(num[i] == num[i+1]) {
            cen = 1;
            break;
        }
    }
    if (cen == 1) {
        puts("NO");
    } else {
        puts("YES");
    }
    return 0;
}