var sh,de:string;
    a:array[1..100]of integer;
    i,n:Integer;
begin
readln(sh);
n:=length(sh);
for i:=1 to n do a[i]:=ord(sh[i])-97;
for i:=2 to n do
  if a[i]<a[i-1] then a[i]:=a[i]+((a[i-1]-a[i])div 26 + 1)*26;
for i:=n downto 2 do a[i]:=a[i]-a[i-1];
a[1]:=a[1]-5;
de:='';
for i:=1 to n do de:=de+chr(97+a[i] mod 26);
writeln(de);
end.

i didn't understand where is my mistake

a[1] can be less than 5.

Thank you

Edited by author 05.08.2011 16:43

Edited by author 05.08.2011 16:43

if you problem input is "adham" . what is output?
output is "vdetm" . You should know if the first letter is "a" or "b" or "c" or "d" or "f"
(char)("a" + 26) is correct way!

You are great! I got the same mistake.