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>
#include<string.h>
 
int main()
{
  long N, same;
  long long A[20002];
  
  scanf("%ld", &N);
  
  for(long i=0;i<N;i++)
  {
      scanf("%lld", &A[i]);
  }
  
  same=0;
  for(int i=0;i<N;i++)
  {
    for(int j=0;j<N;j++)
    {
      if (i==j) continue;
      if (A[i] == A[j]) same++;
    }
  }
  
  if (same==0)
  {
    printf("YES");
  }
           else
           {
             printf("NO");
           }
           
  return 0;
}