Var
 f1,f2:Text;
 N1,N2:String;
 ED:byte;

Function Encode_String(S:String):String;
var
 i,L:byte;
 S1:String;
begin
 S1:='';
 L:=Length(S);
 for i:=1 to L do S1:=S1+Chr(Ord(S[i])+1);
 Encode_String:=S1;
end;

Function Decode_String(S:String):String;
var
 i,L:byte;
 S1:String;
begin
 S1:='';
 L:=Length(S);
 for i:=1 to L do S1:=S1+Chr(Ord(S[i])-1);
 Decode_String:=S1;
end;

Procedure Encode_File(Nm1,Nm2:String);
var S:String;
begin
 Assign(f1,Nm1);
 Reset(f1);
 Assign(f2,Nm2);
 Rewrite(f2);
 Repeat
  Readln(f1,S);
  Writeln(f2,Encode_String(S));
 Until EoF(f1);
 Close(f1);
 Close(f2);
end;

Procedure Decode_File(Nm1,Nm2:String);
var S:String;
begin
 Assign(f1,Nm1);
 Reset(f1);
 Assign(f2,Nm2);
 Rewrite(f2);
 Repeat
  Readln(f1,S);
  Writeln(f2,Decode_String(S));
 Until EoF(f1);
 Close(f1);
 Close(f2);
end;

Begin
 Repeat
  Writeln('Choose the action: 1 - encode');
  Writeln('                   2 - decode');
  Writeln('                   0 - quit');
  Readln(ED);
  Case ED of
   1: begin
       write('Initial file name (full path): ');
       readln(N1);
       write('Encoded file name (full path): ');
       readln(N2);
       Encode_File(N1,N2);
      end;
   2: begin
       write('Encoded file name (full path): ');
       readln(N1);
       write('Decoded file name (full path): ');
       readln(N2);
       Decode_File(N1,N2);
      end;
  end;
  Writeln;
 Until ED=0;
End.