solve m n = if m * n == 0
              then 1
              else solve (m-1) n + solve m (n-1)

solve_memoized m n = last r
  where
    r :: [Int]
    r = map f [(i, j) | i <- [0..m], j <- [0..n]]
    f (0,_) = 1
    f (_,0) = 1
    f (i,j) = c (i-1,j) + c (i,j-1)
    c (k,l) = r !! (k*(n+1)+l)

main = do
  print $ solve 2 2
  print $ solve_memoized 2 2
  print $ solve 3 2
  print $ solve_memoized 3 2

  print $ solve 4 2
  print $ solve_memoized 4 2