Need HELP in REPLACE for X October long : What is wrong in my code

[saurav_009]

Question link: https://www.codechef.com/OCT20B/problems/REPLESX/
Solution Link : https://www.codechef.com/viewsolution/38871067

[hash16]

You missed the upperbound of the number that is to be inserted (in case of multiple presence of the number).