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)

fn main() {
  let (n, m) = {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).unwrap();
    let mut ws = s.split_whitespace(); // 空白区切りの単語に分解する
    let n: i32 = ws.next().unwrap().parse().unwrap(); // イテレータから値を取り出して整数に
    let m: i32 = ws.next().unwrap().parse().unwrap();
    (n, m)
  };

  let mut value = 1;
  let mut count = 0;
  loop {
    if value >= m {
      print!("{}", count);
      break;
    }
    value += n - 1;
    count += 1;
  }
}