Fake Certificate

You are given a binary string $S$ of length $N$, representing the attendance sheet of Alice. For the days when Alice went to school, $S_i = 1$, otherwise, $S_i = 0$. Alice wanted to increase her attendance. She can perform the following operation **at most** once : - Choose any substring of $S$ where Alice was absent **everyday**. She can then give a medical certificate for this period and will