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>

int main(){
 long long int n,i,j,cnt=0;
 long long int a[20000];
   scanf("%lld\n",&n);
   scanf("%lld",&a[0]);
  for(i=0;i<n;i++){
    for(j=i+1;j<n;j++){
      	    scanf("%lld",&a[j]);
   			if(a[i]==a[j]){
          	printf("NO");
          	return 0;
        }
     }
  }
 printf("YES");
 return 0; 
}