B'You are given two strings s and t , each of length n and consisting of lowercase Latin alphabets. You want to make s equal to t . You can perform the following operation on s any number of times to achieve it -- For example, on rotating the substring [2,4] , string "abcde" becomes "adbce". A string a is a substring of a string b if a can be obtained from b by deletion of several (possibly, zero or all) characters from the beginning and several (possibly, zero or all) characters from the end. Find the minimum number of operations required to convert s to t , or determine that it 's impossible. The first line of the input contains a single integer t (1 <= q t <= q 2000) -- the number of test cases. The description of the test cases follows. The first line of each test case contains a single integer n (1 <= q n <= q 2000) -- the length of the strings. The second and the third lines contain strings s and t respectively. The sum of n over all the test cases does not exceed 2000 . For each test case, output the minimum number of operations to convert s to t . If it is not possible to convert s to t , output -1 instead. For the 1 -st test case, since s and t are equal, you don 't need to apply any operation. For the 2 -nd test case, you only need to apply one operation on the entire string ab to convert it to ba. For the 3 -rd test case, you only need to apply one operation on the entire string abc to convert it to cab. For the 4 -th test case, you need to apply the operation twice: first on the entire string abc to convert it to cab and then on the substring of length 2 beginning at the second character to convert it to cba. For the 5 -th test case, you only need to apply one operation on the entire string abab to convert it to baba. For the 6 -th test case, it '...