const
 cxmax=100;
 (* opcodes *)
 lit=1; opr=2; lod=3; sto=4;
 int=6; jmp=7;
 (* opr arguments *)
 neg=1; add=2; sub=3; mul=4;
 divis=5; ret=0;
var
 codefct: array [cxmax] of integer ;
 codea: array [cxmax] of integer ;
procedure interpret;
 const stacksize=200;
 var
  p,b,t: integer ;
  ifct, ia: integer ;
  s: array [stacksize] of integer ;
 begin
  writeln ("start pl/0");
  t:=0; b:=1; p:=0;
  s[0]:=0;
  s[1]:=0; s[2]:=0; s[3]:=0;
  repeat
   ifct:=codefct[p];
   ia:=codea[p];
   p:=p + 1;
   case ifct of
    lit:
     begin
      t:=t + 1;
      s[t]:=ia;
     end ;
    opr:
     case ia of (* operator *)
      ret:
       begin
        t:=b - 1;
        p:=s[t + 3];
        b:=s[t + 2];
       end ;
      neg:
       s[t]:=- s[t];
      add:
       begin
        t:=t - 1;
        s[t]:=s[t] + s[t + 1];
       end ;
      sub:
       begin
        t:=t - 1;
        s[t]:=s[t] - s[t + 1];
       end ;
      mul:
       begin
        t:=t - 1;
        s[t]:=s[t] * s[t + 1];
       end ;
      divis:
       begin
        t:=t - 1;
        s[t]:=s[t] div s[t + 1];
       end
     end ; (* end case ia of *)
    lod:
     begin
      t:=t + 1;
      s[t] := s[1 + ia];
     end ;
    sto:
     begin
      s[1 + ia] := s[t];
      writeln ("> ",s[t]);
      t:=t - 1;
     end ;
    int:
     t:=t + ia;
    jmp:
     p:=ia
   end ;
  until p=0;
  writeln ("end pl/0")
 end ;
begin
 codefct[0]:=jmp; codea[0]:=1;
 codefct[1]:=int; codea[1]:=5;
 codefct[2]:=lit; codea[2]:=3;
 codefct[3]:=sto; codea[3]:=3;
 codefct[4]:=lit; codea[4]:=3;
 codefct[5]:=sto; codea[5]:=4;
 codefct[6]:=lit; codea[6]:=5;
 codefct[7]:=lit; codea[7]:=2;
 codefct[8]:=lod; codea[8]:=3;
 codefct[9]:=opr; codea[9]:=add;
 codefct[10]:=lit; codea[10]:=4;
 codefct[11]:=opr; codea[11]:=mul;
 codefct[12]:=opr; codea[12]:=add;
 codefct[13]:=sto; codea[13]:=3;
 codefct[14]:=lit; codea[14]:=4;
 codefct[15]:=lit; codea[15]:=2;
 codefct[16]:=lod; codea[16]:=3;
 codefct[17]:=opr; codea[17]:=add;
 codefct[18]:=opr; codea[18]:=mul;
 codefct[19]:=lit; codea[19]:=5;
 codefct[20]:=opr; codea[20]:=add;
 codefct[21]:=sto; codea[21]:=3;
 codefct[22]:=lod; codea[22]:=3;
 codefct[23]:=lod; codea[23]:=4;
 codefct[24]:=opr; codea[24]:=sub;
 codefct[25]:=sto; codea[25]:=4;
 codefct[26]:=opr; codea[26]:=ret;
 interpret;
end .