uses crt;
var i,n,d: integer;
a: array[1..100] of integer;
begin
clrscr;
write ('nhap n: '); readln (n);
while n<=0 do
begin
i:=i+1;
a[i]:=n mod 10;
n:=n div 10
d:=d+1;
end;
write ('so sau khi dao nguoc la: ');
for i:=d downto 1 do write (a[i]);
readln;
end.