uses crt;
var s1,s2:string;
function tru(x1,x2:string):string;
var tam:string[2];
du,i,so1,so2:byte;
begin
while length(x1)<>length(x2) do
if length(x1)<length(x2) then insert('0',x1,1)
else insert('0',x2,1);
du:=0; tru:='';
for i:=length(x1) downto 1 do
begin
val(x1[i],so1); val(x2[i],so2);
if so1<(so2+du) then
begin
so1:=10+so1-so2-du;
du:=1;
end
else
begin
so1:=so1-so2-du;
du:=0;
end;
str(so1,tam);
tru:=tam+tru;
end;
while (tru[1]='0') and (length(tru)>1) do delete(tru,1,1);
end;
BEGIN
clrscr;
write('Nhap so thu nhat:'); readln(s1);
write('Nhap so thu hai:'); readln(s2);
write(tru(s1,s2));
readln
END.
Chúc bạn học tốt!
