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 a,flag=1,i,j,b[1000];
    scanf("%d",&a);
    for(i=0;i<a;i++)
    {
        scanf("%d",&b[i]);
    }
    for(i=0;i<a;i++)
    {
        for(j=i+1;j<a;j++)
        {
            if(b[i]==b[j])
            {
                flag=0;
                break;
            }
        }
    }
    if(flag==1)
    {
        printf("YES");
    }
    else
    {
        printf("NO");
    }
}