Given two strings s and t, return the number of distinct subsequences of s which equals t.
The test cases are generated so that the answer fits on a 32-bit signed integer.
Examples
Example 1
Input: s = "rabbbit", t = "rabbit"
Output: 3
There are 3 ways you can generate "rabbit" from s.
Example 2
Input: s = "babgbag", t = "bag"
Output: 5
There are 5 ways you can generate "bag" from s.
Constraints
1 <= s.length, t.length <= 1000sandtconsist of English letters