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 <stdlib.h>
int A[200005]= {0};
int main()
{
    int N;
    scanf("%d",&N);
    int i,ii;
    int val;
    int flag=0;
    for(i=0; i<N; i++)
    {
        scanf("%d",&val);
        for(ii=0; ii<i; ii++)
        {
            if(A[ii]==val)
            {
                flag=1;break;
            }
        }
        if(flag==0)
        {
            A[i]=val;
        }
    }
    if(flag==0)
    {
        printf("YES");
    }
    else
    {
        printf("NO");
    }

    return 0;
}