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<stdlib.h>

int main(void){
  int N;
  int *A;
  int flag = 0;

  scanf("%d",&N);

  A = (int *)malloc(N);
   if(A == NULL) {
      exit(EXIT_FAILURE);
   }

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

  for(int i = 0; i < N; i++){
    for(int j = 0; j < N; j++){

      if(A[i] == A[j]){
        if(i == j)continue;

        flag = 1;
        goto end;
      }
    }
  }

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

  return 0;
}