Find the String

Two strings $A$ and $B$ made of lowercase English letters are called effectively equal if all of the following hold.

1. $A$ and $B$ have the same length.
2. For all integers $i$ and $j$, if the $i$-th and $j$-th characters of $A$ are equal, then the $i$-th and $j$-th characters of $B$ are equal.
3. For all integers $i$ and $j$, if the $i$-th and $j$-th characters of $A$ are different, then the $i$-th and $j$-th characters of $B$ are different.

For example, $A =$aba and $B =$pqp are effectively equal. However, $A =$abca and $B =$abcb are not an effectively equal pair.

Given strings $T$ and $P$, write a program that counts the contiguous substrings of $T$ that are effectively equal to $P$.

For example, if $T =$abababbab and $P =$pqp, then the five substrings aba, bab, aba, bab, bab starting from the left of $T$ are effectively equal to $P$.

You must write the following function.

• int findP( char T [], char P [], int N, int M ): T is an array (string) of length N+1. P is an array of length M+1. T and P store lowercase strings of length N and M. The last position of T and P holds \0. findP must return the number of contiguous substrings of T that are effectively equal to P.

$1 \le N \le 1\,000\,000$, $1 \le M \le N$.