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: Wrong Answer)

#include <stdbool.h>
#include <stdio.h>

bool array_check(const int* array, size_t size){

  for (size_t i = 0; i < size - 1; ++i) {
    for (size_t j = i + 1; j < size; ++j) {

      if (array[i] == array[j]) {
        return false;
      }

    }
  }

  return true;
}

int main(void){
  int N;
  int A[200001];
  int flag;

  scanf("%d",&N);

  for(int i = 0; i < N; i++){
    scanf("%d",&A[i]);
  }

  flag = array_check(A,N);

  if(flag == 0){
    printf("N0\n");
  }
  else if(flag == 1){
    printf("YES\n");
  }

  return 0;
}