by any chance 123.456e+5 is not considered as possible output or it is not decimal number. Right?
No not at all. This will never be a output nor it will be resultant no. after all the substitutions.
Btw please dont ask questions about the ongoing contest on the forum try reading the problem statement more and more times to figure out the possible input and output.
please dont use the tag ‘query’ for such questions.