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)

pub fn main() {
    let mut buf = String::new();
    std::io::stdin().read_line(&mut buf).unwrap();
    let n: usize = buf.trim().parse().unwrap();
    use std::collections::HashSet;
    let mut set: HashSet<u64> = HashSet::with_capacity(n);
    buf.clear();
    std::io::stdin().read_line(&mut buf).unwrap();
    for w in buf.split_whitespace() {
        let a: u64 = w.parse().unwrap();
        if !set.insert(a) {
            println!("NO");
            return;
        }
    }
    println!("YES");
}