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() {
    // loop{ //For test
        solve();
    // }
}

#[allow(dead_code)]
fn solve(){
    let mut n: i64 = read();
    let mut a: Vec<i64> = read_vec();
    let uniq: HashSet<i64> = a.clone().into_iter().collect();
    if a.len() == uniq.len()  {
        println!("YES");
    } else{
        println!("NO");
    }
}

fn is_even(arr: &Vec<i32>) -> bool {
    return arr.iter().all(|x| x%2==0);
}

/// 標準入力から一行を読み取り、指定の型に変換する関数
#[allow(dead_code)]
fn read<T: std::str::FromStr>() -> T {
    let mut s = String::new();
    let _ = std::io::stdin().read_line(&mut s);
    s.trim().parse().ok().unwrap()
}

/// 標準入力から一行を読み取り、空白文字で分割し、各要素を指定の型に変換する関数
#[allow(dead_code)]
fn read_vec<T: std::str::FromStr>() -> Vec<T> {
    read::<String>().split_whitespace()
        .map(|e| e.parse().ok().unwrap()).collect()
}

/// 標準入力からn行を読み取り、各行を空白文字で分割し、各要素を指定の型に変換する関数
#[allow(dead_code)]
fn read_vec2<T: std::str::FromStr>(n: u32) -> Vec<Vec<T>> {
    (0..n).map(|_| read_vec()).collect()
}