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>
#include <stdlib.h>
int int_sort(const void *a,const void *b){
	if( *(int *)a < *(int *)b){
		return -1;
	}else 
	if(*(int *)a == *(int *)b){
		return 0;
	}
	return 1; 
}
int main(void){
	int N;
	int i;
	int j;
	int a=0;
	if(scanf("%d",&N) < 1){
		fprintf(stderr,"error\n");
		exit(1);
	}
	
	int A[N];
	for(i=0;i<N;i++){
		if(scanf("%d",&A[i]) < 1){
			fprintf(stderr,"error\n");
			exit(1);
		}
	}
	qsort((void *)A,N,sizeof(int),int_sort);
	for(i=0;i<N;i++){
		if(A[i] == A[i+1]){
			a=1;
		}
	}
	
	if(a==1){
		printf("No\n");
	}else{
		printf("Yes\n");
	}
	
	return 0;
}