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 Haskell (GHC 7.10.3) (judge verdict: Accepted)

module Main where
    import Data.List
    import Control.Monad
    
    main = do
        {-
        n <- getLine
        lines<-getLines (read n ::Int)
        -}        
        inputs<-getInputs        
        print ( foldr (*) 1 (map pred inputs))
        
        
    read' s = read s ::Integer

    getInputs = do
        line <- getLine
        let inputs = map read' (words line)
        return inputs

    getLines n = do
        lines <- (replicateM n getLine)
        return lines

    getGCD::Integer->Integer->Integer
    getGCD m n 
        | m < n = (getGCD n m)
        | n == 0 = m
        | otherwise = getGCD (mod m n) n

    getLCM::Integer->Integer->Integer
    getLCM m n = div (m * n) (getGCD m n)