стек и очередь

program lab2;
uses crt;
const lo=15; ls=10;
type st15=string[15];
ms=array[1..10] of st15;
var is,io,nm:integer;
a:st15; st,och:ms;
 
procedure inp_a(var s:st15);
begin
write('a=');readln(s);end;
 
procedure out_a(var s:st15);
begin
writeln('a=',a);end;
 
procedure dop_st(a:st15; ls:integer; var is:integer; var st:ms);
begin is:=is+1;
st[is]:=a;
end;
procedure dop_och(a:st15; ls:integer; var is:integer; var st:ms);
begin is:=is+1;
st[is]:=a;
end;
 
procedure from_st(var a:st15; ls:integer; var is:integer; var st:ms);
begin a:=st[is];
st[is]:=' ';
is:=is-1;
end;
 
procedure from_och(var a:st15; ls:integer; var is:integer; var st:ms);
var i:integer;
 
begin a:=st[1];
for i:=1 to is-1 do;
st[i]:=st[i+1];
st[is]:=' ';
is:=is-1;
end;
procedure out_st(a:string; is:integer; st:ms);
var i:integer;
begin
writeln(a);
for i:=1 to is do
writeln(st[i]);
end;
procedure save_ma(name:string; var m:ms; var n:integer); var i:integer; F:text;
begin assign(F,name);
rewrite(F); for i:=1 to n do;writeln(F,m[i]);
close(F);
end;
procedure read_ma(name:string; var m:ms; var n:integer); var i:integer; F:text;
begin assign(F,name);
reset(F);n:=0;while not EOF(F) do
begin n:=n+1; readln(F,m[n]);end;
close(F);
end;
 
BEGIN
is:=0; io:=0; a:=' ';
repeat
clrscr;
window(1,1,80,25); clrscr;
gotoxy(25,15);
out_a(a);
window(1,1,20,25);
out_st('stek',is,st);
window(61,1,80,25);
out_st('och',io,och);
window(26,1,55,12);
writeln('1-con->a');
writeln('2-a->tovar');
writeln('3-tovar->a');
writeln('4-a->pokupatel');
writeln('5-pokupatel->a');
writeln('6-save');
writeln('7-read');
write('input 1-8');
readln(nm);
case nm of
1:inp_a(a);
2:if is=ls then
begin
writeln('Stek p');
write('press');
readln;
end
else
dop_st(a,ls,is,st);
3:begin
if is=0 then
begin
writeln('Stek p');
write('press');
readln;
end
else
from_st(a,ls,is,st);
end;
 
4:if io=lo then begin writeln('och p');
write('press');
readln;
end
else dop_och(a,lo,io,och);
5:if io=0 then begin writeln('och p');
write('press');
readln;
end
else from_och(a,lo,io,och);
 
6: begin save_ma ('C:\Users\User\Desktop\och.txt',och,io);
save_ma ('C:\Users\User\Desktop\stek.txt',st,is); end;
7:begin read_ma('C:\Users\User\Desktop\och.txt',och,io);
read_ma ('C:\Users\User\Desktop\stek.txt',st,is);end;
end;
until (nm=10);
END.