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>

int main(){
    int N;
    scanf("%d", &N);

    int i,j,tmp;
    int A[200000+1] = {0};
    for( i = 0; i < N; i++ ){
        scanf("%d", &A[i]);
    }

    for( i = 0; i < N; i++ ){
        for( j = i+1; j < N; j++ ){
            if( A[i] > A[j] ){
                tmp = A[i];
                A[i] = A[j];
                A[j] = tmp;
            }
        }
    }

    
    for( i = 0; i < N-1; i++ ){
        if( A[i] == A[i+1] ){
            printf("NO\n");
            return 0;
        }
    }

    printf("YES\n");

    return 0;
}