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  1. program indexing;
  2.  
  3. var
  4. A, B, C : AnsiString;
  5. dimA, dimB,i, n :Longint;
  6. begin
  7. (*assign(input, 'input.txt'); reset(input);
  8.   assign(output, 'output.txt'); rewrite(output);*)
  9.  
  10. ReadLn(A);
  11.  
  12. ReadLn(B);
  13.  
  14. C := '';
  15.  
  16. dimA:=Length(A); dimB:=Length(B);
  17. i:=1;
  18. if dimA<=dimB then
  19. begin
  20. while ((ord(B[i]) - ord(A[i]))<1) and (i<= dimA) do begin C:=C+A[i]; i:=i+1; end;
  21. if i<=dimA then begin n:= ord(A[i])+1; C:=C+chr(n); end
  22. else begin
  23. if (B[dimA+1]<>'a') then C:=C+'a'
  24. else begin if dimB>dimA+1 then C:=C+'a'
  25. else C:='-1'; end;
  26. end
  27. end
  28. else
  29. begin
  30. while (A[i]=B[i]) and (i<=dimB) do begin C:=C+A[i]; i:=i+1; end;
  31. while (ord(B[i]) - ord(A[i]))=1 do begin C:=C+A[i]; i:=i+1; end;
  32. if A[i]<>'z' then begin n:= ord(A[i])+1; C:=C+chr(n); end
  33. else begin while A[i]='z' do begin C:=C+'z'; i:=i+1 ; end; C:=C+'z';end;
  34.  
  35. end;
  36. writeln(C);
  37. end.
Success #stdin #stdout 0s 5288KB
stdin
abcd
abcd
stdout
abcda