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: Wrong Answer)

use std::io::{self, Read};

fn main() {
    let mut buffer = String::new();
    io::stdin().read_to_string(&mut buffer);

    let st: Vec<&str> = buffer.split_terminator(" ").map(|v| v.trim()).collect();

    let f = st.get(0).unwrap().parse::<f32>().unwrap();
    let s = st.get(1).unwrap().parse::<f32>().unwrap();

    if s == 1.0 {
        println!("0")
    } else if f >= s {
        println!("1");
        return;
    } else if f == 2.0 {
        println!("{}", ((s as usize) - 1));
    } else {
        println!("{}", (s / f).ceil() as usize);
    }

    // println!("{}", ((s - f) / (f - (1 as f32))).ceil() + (1 as f32));
}