Problem:
Score : 200 points

Problem Statement

Snuke is interested in strings that satisfy the following conditions:

The length of the string is at least N.

The first N characters equal to the string s.

The last N characters equal to the string t.

Find the length of the shortest string that satisfies the conditions.

Constraints

1≤N≤100

The lengths of s and t are both N.

s and t consist of lowercase English letters.

Input

The input is given from Standard Input in the following format:

N
s
t

Output

Print the length of the shortest string that satisfies the conditions.

Sample Input 1

3
abc
cde

Sample Output 1

5

The shortest string is abcde.

Sample Input 2

1
a
z

Sample Output 2

2

The shortest string is az.

Sample Input 3

4
expr
expr

Sample Output 3

4

The shortest string is expr.

Solution in Rust (1.15.1) (judge verdict: Wrong Answer)

use std::io;

macro_rules! parse_input {
    ($x:expr, $t:ident) => ($x.parse::<$t>().unwrap())
}

macro_rules! parse_inputs {
    ($x:expr, $t:ident) => ($x.map(|s| s.parse::<$t>().unwrap()).collect::<Vec<$t>>())
}

macro_rules! print_err {
    ($($arg:tt)*) => (
        {
            use std::io::Write;
            writeln!(&mut ::std::io::stderr(), $($arg)*).ok();
        }
    )
}

fn main() {
    let mut input_line = String::new();
    io::stdin().read_line(&mut input_line).unwrap();
    let n = parse_input!(input_line.trim(), u32);

    let mut input_line = String::new();
    io::stdin().read_line(&mut input_line).unwrap();
    let ss = input_line.trim();
    // let test :() = ss;

    let mut input_line = String::new();
    io::stdin().read_line(&mut input_line).unwrap();
    let ts = input_line.trim();

    let mut ans = 0;

    for i in 0..n {
        let a = &ss[(i as usize)..(n as usize)].to_string();
        let b = &ts[0..((n - i) as usize)].to_string();
        if a == b {
            ans = n + i;
        }
    }
    if ans == 0 {
        ans = n * 2;
    }
    println!("{}", ans);
}