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::collections::HashSet;

fn main() {
    let n: usize = {
        let mut n = String::new();
        std::io::stdin().read_line(&mut n).ok();
        n.trim().parse().unwrap()
    };

    let mut line = String::new();
    std::io::stdin().read_line(&mut line).ok();
    let line: HashSet<i32> = line.split_whitespace()
                                   .map(|c|c.parse().unwrap())
                                   .collect();
    println!("{}", if n == line.len() { "YES" } else { "NO" });
}