function Battage(const S1, S2, S: string): Boolean;
var
i: Integer;
Index1, Index2: Integer;
begin
Result := False;
if S1 = '' then
Result := S = S2;
if S2 = '' then
Result := S = S1;
Index1 := 1;
Index2 := 1;
for i := 1 to Length(S) do
begin
if S[i] = S1[Index1] then
Inc(Index1)
else
if S[i] = S2[Index2] then
Inc(Index2)
else
Exit;
end;
Result := Length(S) = Length(S1) + Length(S2);
end;