Time limit : 2sec / Memory limit : 256MB
You are given a string $S$ consisting of
1. Find the maximum integer $K$ not greater than $|S|$ such that we can turn all the characters of $S$ into
0 by repeating the following operation some number of times.
Choose a contiguous segment $[l,r]$ in $S$ whose length is at least $K$ (that is,$r-l+1\geq K$ must be satisfied). For each integer $i$ such that $l\leq i\leq r$, do the following: if $S_i$ is
0, replace it with
1; if $S_i$ is
1, replace it with