A substring of a string T is defined as:

Given two strings A, B and one integer K, we define S, a set of triples (i, j, k):

You are to give the value of |S| for specific A, B and K.

The input file contains several blocks of data. For each block, the first line contains one integer K, followed by two lines containing strings A and B, respectively. The input file is ended by K=0.

1 ≤ |A|, |B| ≤ 10⁵
1 ≤ K ≤ min{|A|, |B|}
Characters of A and B are all Latin letters.