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 <stdio.h>

int main(){
   int n,flag=0;
   int a[200000];
   scanf("%d",&n);
   for(int i = 0;i < n;i++){
      scanf("%d",&a[i]);
   }
   for(int i = 0;i < n;i++){
      for(int j = i + 1;j < n;j++){
         //printf("%d %d\n",a[i],a[j]);
         if(a[i] == a[j]){
            flag = 1;
            break;
         }
      }
      if(flag == 1)break;
   }
   if(flag == 1) printf("No");
   else if(flag == 0) printf("Yes");
}