P16104 [ICPC 2019 NAIPC] Subsequences in Substrings

You are given two strings $s$, and $t$. Count the number of substrings of $s$ that contain $t$ as a subsequence at least once. Note that a *substring* and a *subsequence* both consist of characters from the original string, in order. In a *substring*, the characters must be contiguous in the original string, but in a *subsequence*, they are not required to be contiguous. In the string **abcde**, **ace** is a *subsequence* but not a *substring*. If $s$ is **aa** and $t$ is **a**, then the answer is 3: [**a**]a, [**aa**], and a[**a**].

Each test case will consist of exactly two lines. The first line will contain string $s$ ($1 \leq |s| \leq 10^5$, $s \in [a-z]^*$), with no other characters. The second line will contain string $t$ ($1 \leq |t| \leq 100$, $|t| \leq |s|$, $t \in [a-z]^*$), with no other characters.

Output a single integer, which is the number of substrings of $s$ that contain $t$ as a subsequence at least once.