Problem:
Score : 200 points

Problem Statement

Takahashi's house has only one socket.

Takahashi wants to extend it with some number of power strips, each with A sockets, into B or more empty sockets.

One power strip with A sockets can extend one empty socket into A empty sockets.

Find the minimum number of power strips required.

Constraints

All values in input are integers.

2 \leq A \leq 20

1 \leq B \leq 20

Input

Input is given from Standard Input in the following format:

A B

Output

Print the minimum number of power strips required.

Sample Input 1

4 10

Sample Output 1

3

3 power strips, each with 4 sockets, extend the socket into 10 empty sockets.

Sample Input 2

8 9

Sample Output 2

2

2 power strips, each with 8 sockets, extend the socket into 15 empty sockets.

Sample Input 3

8 8

Sample Output 3

1

Solution in Rust (1.15.1) (judge verdict: Accepted)

use std::io;
use std::str::FromStr;

fn read<T: FromStr>() -> T {
    let mut s = String::new();
    io::stdin().read_line(&mut s).unwrap();
    s.trim().parse().ok().unwrap()
}
fn read_two<T: FromStr>() -> (T, T) {
    let mut s = String::new();
    io::stdin().read_line(&mut s).unwrap();
    let mut x = s.split_whitespace().map(|x| x.parse().ok().unwrap());
    (x.next().unwrap(), x.next().unwrap())
}

fn main() {
    let (mut a, mut b)= read_two::<i32>();
    a -= 1;
    b -= 1;
    let x = if b % a == 0 {
        b / a
    } else {
        b / a + 1
    };
    println!("{}", x);
}