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 i;
    int n;

    scanf("%d", &n);
    //printf("n = %d\n", n);
    char c[n*10^10];
    int num[n];

    for (i=0;i<n;i++)
    {
    scanf("%s", c);
    //printf("c = %s \n", c);
    num[i]= atoi(c);
    //printf("num = %d \n", num[i]);
    }
    int j;
    for (i= 0;i<n-1;i++)
    {
        for (j=i+1;j<n;j++)
        {
            if(num[i]==num[j])
            {
                printf("NO");
                return 0;
            }
        }
    }
    printf("YES");
    //scanf("%s", c);
    //printf("c = %s\n", c);
    return 0;
}