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;
fn solve(a: usize, b: usize) -> usize {
    let q = (b - 1) / (a - 1);
    if q * (a - 1) < b - 1 {
        q + 1
    } else {
        q
    }
}

#[test]
fn test_solve() {
    assert_eq!(solve(4, 10), 3);
    assert_eq!(solve(8, 9), 2);
    assert_eq!(solve(8, 8), 1);
    assert_eq!(solve(8, 1), 0);
}

fn main() {
    let mut input = String::new();
    io::stdin().read_line(&mut input).unwrap();
    let mut iter = input.split_whitespace();
    let a: usize = iter.next().unwrap().parse().unwrap();
    let b: usize = iter.next().unwrap().parse().unwrap();
    println!("{}", solve(a, b))
}