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 (1.15.1) (judge verdict: Accepted)

use std::io::{stdin, stdout, Write};
use std::collections::HashMap;

fn main() {
    let out = stdout();
    let mut out = out.lock();
    let mut first_line = String::new();
    stdin().read_line(&mut first_line).unwrap();
    let n: usize = first_line.trim().parse().unwrap();

    let mut second_line = String::new();
    stdin().read_line(&mut second_line).unwrap();
    let v: Vec<&str> = second_line.split_whitespace().collect();
    let mut map =HashMap::new();
    for i in 0..n {

        if map.contains_key(v[i]) {
            write!(out, "NO").unwrap();
            return;
        }
        map.insert(v[i], "");
    }
    write!(out, "YES").unwrap();
}