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: Time Limit Exceeded)

#include<stdio.h>
#include<string.h>
int main()
{
    long n,flag=1;
    scanf("%ld",&n);
    long a[n];
    for(long i=0;i<n;i++)
    {
        scanf("%ld",&a[i]);
    }
    for(long i=0;i<n-1;i++)
    {
        for(long j=i+1;j<n;j++)
        {
            if(a[i]==a[j])
            {
                flag=0;
                break;
            }
        }
    }
    if(flag==1)
        printf("YES");
    else
        printf("NO");
    return 0;
}