B'A binary string is a string consisting only of the characters 0 and 1. You are given a binary string s_1 s_2 ldots s_n . It is necessary to make this string non-decreasing in the least number of operations. In other words, each character should be not less than the previous. In one operation, you can do the following: What is the minimum number of operations needed to make the string non-decreasing? Each test consists of multiple test cases. The first line contains an integer t ( 1 <= q t <= q 10^4 ) -- the number of test cases. The description of test cases follows. The first line of each test cases a single integer n ( 1 <= q n <= q 10^5 ) -- the length of the string. The second line of each test case contains a binary string s of length n . It is guaranteed that the sum of n over all test cases does not exceed 2 cdot 10^5 . For each test case, output a single integer -- the minimum number of operations that are needed to make the string non-decreasing. In the first test case, the string is already non-decreasing. In the second test case, you can select i = 1 and then s = mathtt{01} . In the third test case, you can select i = 1 and get s = mathtt{010} , and then select i = 2 . As a result, we get s = mathtt{001} , that is, a non-decreasing string. In the sixth test case, you can select i = 5 at the first iteration and get s = mathtt{100001} . Then choose i = 2 , then s = mathtt{111110} . Then we select i = 1 , getting the non-decreasing string s = mathtt{000001} . '...