Merkkijono

use std::io::stdin;

const MERKIT: [char; 16] = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p'];

fn main() {
    let mut n = String::new();
    stdin().read_line(&mut n).unwrap();
    let n: usize = n.trim_end().parse().unwrap();

    if n == 1 {
        print!("a");
        return;
    }

    let mut effa = String::with_capacity(100);
    effa.push('b');
    for i in 3..=n {
        let mut temp = effa.len();
        
        while temp != 0 {
            effa.insert(temp, MERKIT.get(i-1).unwrap().clone());
            temp -= 1;
        }
        effa.insert(0, MERKIT.get(i-1).unwrap().clone());
    }
    
    let mut ulos = String::with_capacity(effa.len()*2+1);

    ulos.push_str(&effa);
    ulos.push('a');
    ulos.push_str(&effa);

    print!("{}", ulos)
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED

Test 14

Verdict: ACCEPTED

Test 15

Verdict: ACCEPTED

Test 16

Verdict: ACCEPTED