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 Rust (1.42.0) (judge verdict: Accepted)

use text_io::*;
use std::collections::*;
use std::process::exit;

fn main() {
    let mut a:usize = read!();
    let mut v = HashMap::new();
    for i in 0..a {
        let y:usize = read!();
        let z: &usize = v.get(&y).unwrap_or(&0);
        if z!=&0 {
            println!("NO");
            exit(0);
        }
        v.insert(y,1);
    }
    println!("YES");
}