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 main(void){
  int A[200000];
  int i,j;
  int N,flag;
  
  scanf("%d",&N);
  for(i=0;i<N-1;i++){
    scanf("%d ",&A[i]);
  }
  scanf("%d",&A[N-1]);
  
  for(i=0;i<N-1;i++){
    for(j=i+1;j<N;j++){
      if(A[i] == A[j]) {
        flag++;
        break;
      }
    }
    if(flag) break;
  }
  if(flag) printf("NO");
  else printf("YES");
  return 0;
}