program vi4itanie;
Uses Crt;
type cipari=array[1..24] of string; {cipari-cifri}
var s1,s2,r,sk1,sk2: string;
    a1,a2: char;
    i,l1,l2,l,t,sk,g: integer;
    c:cipari;   {cipari-cifri}
    a,b:longint;

procedure burti(var sk:string); {burti-bukvi}
var i,l:integer;
    a:longint;
begin
l:=length(sk);
for i:=1 to l do begin
a:=ord(sk[i]);
if (a>=97) and (a<=122) then begin
                             a:=a-24;
                             sk[i]:=(Chr(a));
                             end;
end;
end;

function parveide(w:char):integer; {malejnkie bukvi
peredelivajutsa v bolj6ie}
begin
case w of
       '0'..'9': parveide:=ord(w)-48;
       else parveide:=ord(upcase(w))-55;
end;
end;

begin
ClrScr;
repeat
writeln('Ievadiet mazinaamo:'); {vvedite umenj6aemoe}
readln(sk1);
burti(sk1); {burti - bukvi}
l1:=length(sk1);
for i:=1 to l1 do
a:=ord(sk1[i]);
if not ((a in [48..57]) or (a in [65..70]))
then writeln('Skaitlis ir ievadits nepareizi!'); {4islo napisano
nepraveljno}
until ((a in [48..57]) or (a in [65..70]));

repeat
writeln('Ievadiet mazinaataaju:');{vvedite vi4itaemoe}
readln(sk2);
burti(sk2); {burti- bukvi}
l2:=length(sk2);
for i:=1 to l2 do
b:=ord(sk2[i]);
if not ((b in [48..57]) or (b in [65..70]))
then writeln('Skaitlis ir ievadits nepareizi!'); {4islo vvedeno nepraveljno}
until ((b in [48..57]) or (b in [65..70]));

for i:=1 to l1 do s1[l1-i+1]:=sk1[i];
for i:=1 to l2 do s2[l2-i+1]:=sk2[i];
if l1>l2 then l:=l1 else l:=l2;
t:=0; r:='';
for i:=1 to l do
begin
a1:='0'; a2:='0';
if i<=l1 then a1:=s1[i];
if i<=l2 then a2:=s2[i];
sk:=parveide(a1)-parveide(a2)-t; {peredelka}
t:=sk div 16;
g:=sk mod 16;
if g<10 then r:=r+chr(g+48) else r:=r+chr(g+55);
if (t>0) and (i=l) then r:=r+'1';
end;
writeln; writeln(sk1); writeln('-'); writeln(sk2);
writeln('Starpiiba ir: ');{raznostj}
for i:=length(r) downto 1 do write(r[i]);
readkey
end.