Problem:
Score : 100 points

Problem Statement

In K-city, there are n streets running east-west, and m streets running north-south. Each street running east-west and each street running north-south cross each other. We will call the smallest area that is surrounded by four streets a block. How many blocks there are in K-city?

Constraints

2 ≤ n, m ≤ 100

Input

Input is given from Standard Input in the following format:

n m

Output

Print the number of blocks in K-city.

Sample Input 1

3 4

Sample Output 1

6

There are six blocks, as shown below:

Sample Input 2

2 2

Sample Output 2

1

There are one block, as shown below:

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

use std::error::Error;
use std::io;

fn main() {
    if let Err(e) = run() {
        println!("{}", e);
    }
}

fn run() -> Result<(), Box<Error>> {
    let mut nm = String::new();
    io::stdin().read_line(&mut nm)?;
    let a: Vec<u64> = nm.trim().split(" ").map(|e| e.parse().expect("")).collect();
    println!("{}", (a[0] - 1) * (a[1] - 1));
    Ok(())
}