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<string.h>
#include<stdbool.h>

int main(void){
    bool flag=false;
    int n,a[200000]={0},s;
    scanf("%d",&n);
    for(int b=0;b<n;b++){
        scanf("%d",&s);
        a[b]=s;
    }
    for(int c=0;c<n-1;c++){
        for(int d=c+1;d<=n;d++){
            if(a[c]==a[d]){
                flag=true;
            }
        }
    }
    if(flag){
        printf("NO");
    }else printf("YES");
}