**String Formation**

Given an array of strings, each of the same length, and a target string, construct the target string using characters from the strings in the given array such that the indices of the characters in the order in which they are used form a strictly increasing sequence. Here the index of a character is the position at which it appears in the string. Note that it is acceptable to use multiple characters from the same string.

Determine the number of ways to construct the target string. One construction is different from another if either the sequences of indices they use are different or the sequences are the same but there exists a character at some index such that it is chosen from a different string in these constructions. Since the answer can be very large, return the value modulo (10^9 + 7).

Consider an example with n = 3 strings, each of length 3. Let the array of strings

OA代做服务，代面试服务，面试辅助服务等，我们均有提供。欢迎联系我。

The next part consists of multiple-choice questions for about 15 minutes. Don't stress about this section; just answer honestly according to your true thoughts, there's no need to try to guess the correct answers.

我们提供OA代做服务，请注意，如果你是在OA的过程中搜索到本文，那么不幸的是我们将无法为您服务。得益于我们优质的服务和有竞争力的价格，我们的OA代做服务必须要预约才能够实行。我们的OA代做是一项收费服务，如果是希望免费获得答案的人不要联系我们。

If you're afraid that you can't solve the OA on your own, please scan the code to contact me or telegram