B"You are given a binary string S of length n indexed from 1 to n . You can perform the following operation any number of times (possibly zero): Choose two integers l and r ( 1 <= l <= r <= n ). Let cnt_0 be the number of times 0 occurs in S[l ldots r] and cnt_1 be the number of times 1 occurs in S[l ldots r] . You can pay |cnt_0 - cnt_1| + 1 coins and sort the S[l ldots r] . (by S[l ldots r] we mean the substring of S starting at position l and ending at position r ) For example if S = 11001, we can perform the operation on S[2 ldots 4] , paying |2 - 1| + 1 = 2 coins, and obtain S = 10011 as a new string. Find the minimum total number of coins required to sort S in increasing order. The first line contains a single integer t ( 1 <= t <= 1000 ) -- the number of test cases. The description of test cases follows. The first line of each test case contains a single integer n ( 1 <= n <= 2 cdot 10^5 ) -- the size of S . The second line of each test case contains a binary string S of n characters S_1S_2 ldots S_n . ( S_i = 0 or S_i = 1 for each 1 <= i <= n ) It is guaranteed that the sum of n over all test cases doesn't exceed 2 cdot 10^5 . For each test case, output the minimum total number of coins required to sort S in increasing order. In the first test case, S is already sorted. In the second test case, it's enough to apply the operation with l = 1, r = 2 . In the third test case, it's enough to apply the operation with l = 1, r = 2 . "...