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::stdin;

fn input () -> (usize, usize) {
    let mut a = String::new();
    stdin().read_line(&mut a).unwrap();
    let a: Vec<usize> = a.trim().split_whitespace().flat_map(str::parse).collect();
    (a[0], a[1])
}

fn main () {
    let (a, b) = input();
    let mut c = 1;
    let mut r = 0;

    while c < b {
        c = a + c - 1;
        r += 1;
    }

    println!("{}", r);
}