% Copyright Massachusetts Institute of Technology 1980, 1989

_longsub = proc (x1, x2, x3, y1, y2, y3: int) returns (int, int, int)
	x3 := x3 - y3
	if x3 < 0
	   then x2 := x2 - 1
		x3 := x3 + 1000
	   end
	x2 := x2 - y2
	if x2 < 0
	   then x1 := x1 - 1
		x2 := x2 + 1000
	   end
	return(x1 - y1, x2, x3)
	end _longsub