%begin
%integer i,k,a,b,p,q, max
%real m,n,r,t,x,y,h,v
%real xmin,xmax,ymin,ymax
%externalroutinespec prompt(%string (255) s)
prompt("xmin,xmax,ymin,ymax?")
read(xmin); read(xmax); read(ymin); read(ymax)
select output(1)
k=1000
max = 0
h=(xmax-xmin)/79
v = (ymax-ymin)/21
%cycle q = 0, 1, 21
%cycle p = 0, 1, 79
   m = xmin+p*h
   n = ymin+q*v
   i = 0; x= 0; y = 0
   %cycle
      r = x*x+y*y
      t = x*x-y*y+m
      y = 2*x*y+n
      x = t
      i = i+1
      %if r > 100 %then %exit
      %if i = k %then i = 0 %and  %exit
   %repeat
!   %if i > max %then max = i
   %if i = 0 %then  space %elsestart
       %if i > 100 %start
          %if i > 150 %then printsymbol('.') %else printsymbol(':')
       %finishelsestart
          printsymbol(i&7+'0')
       %finish
   %finish
%repeat
newline
%repeat
select output(0)
!printstring("deepest point was:"); write(max, 1); newline
%endofprogram