! Plot a histogram from a stream of nonzero integers.

let
	const mid ~ 40;
	var n : Integer;

	proc putmany (c : Char, n : Integer) ~
		let
			var i : Integer
		in
	  begin
			i := 0;
			while i < n do
				begin put (c); i := i + 1 end
		 end;

	proc makenonnegative (var n : Integer) ~
		if n < 0 then n := 0 - n else

in
	begin
	getint (var n); geteol ();
	while n \= 0 do
		begin
		putmany (' ', if n > 0 then mid else mid + n);
		makenonnegative (var n);
		putmany ('+', n);
		puteol ();
		getint (var n); geteol ()
		end
	end