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 (Clang 3.8.0) (judge verdict: Runtime Error)

#include <stdio.h>

int main(int argc, char* argv[]){
    int index, pivot, comparison;
    /*データ入力部分.開始*/
    long n;
    scanf("%ld",&n);
    long a[n];
    for(index=0; index<n; index++)   scanf("%ld",&a[index]);
    /*データ入力部分.終了*/
    
    while(pivot != n){
        for(comparison = pivot+1; comparison<n; comparison++){
            if(a[pivot] == a[comparison]) /*比較結果が同じだった場合*/{
                printf("NO \n");
                return 0;
            }
        }
        pivot++; /*基準値のインクリメント*/
    }
    printf("YES \n");
    return 0;
}