program mahoa;
var S,S1:string;ch:char;i,k:integer;
begin
write('moi ban nhap xau:');readln(S);
S1:='';
for i:=1 to length(S) do
begin
if S[i]='z' then ch:='a' else
begin
k:=ord(S[i]); k:=k+1; ch:=chr(k);
end;
S1:=S1+ch;
end;
writeln('Xau duoc ma hoa la:',S1);
write('moi ban nhap xau can giai ma :');readln(S);
S1:='';
for i:=1 to length(S) do
begin
if S[i]='a' then ch:='z' else
begin
k:=ord(S[i]); k:=k-1; ch:=chr(k);
end;
S1:=S1+ch;
end;
write('xau sau khi duoc giai ma:',S1);
readln;
end.