val file = TextIO.openIn "day_1.txt";
val input = TextIO.inputAll file;
TextIO.closeIn file;

val result =
    let val lines = String.tokens (fn (char) => char = #"\n") input
    in
		let val numbers = map
			(fn (line) =>
				let val digits = List.filter Char.isDigit (String.explode line)
				in Int.fromString (String.implode [List.hd digits, List.last digits]) end)
			lines
		in
			let val numbers = map Option.valOf (List.filter Option.isSome numbers)
			in
				List.foldl (fn (v, acc) => v + acc) 0 numbers
			end
		end
	end;