let rec happyday ?(day=0) ?(count=0) month last =
  if day > last then count
  else
    let digit1 = day mod 10 in
    let sum = (( day - digit1 ) / 10) + digit1 in
    if sum = month then
      happyday ~day:(day + 1) ~count:(count + 1) month last
    else
      happyday ~day:(day + 1) ~count:count month last

let () =
  print_int ( happyday 1 31 +
		happyday 2 28 +
		happyday 3 31 +
		happyday 4 30 +
		happyday 5 31 +
		happyday 6 30 +
		happyday 7 31 +
		happyday 8 31 +
		happyday 9 30 +
		happyday 10 31 +
		happyday 11 30 +
		happyday 12 31
	    );
  print_newline ()