B"You are given a binary string s of length n . Let's define d_i as the number whose decimal representation is s_i s_{i+1} (possibly, with a leading zero). We define f(s) to be the sum of all the valid d_i . In other words, f(s) = sum limits_{i=1}^{n-1} d_i . For example, for the string s = 1011 : In one operation you can swap any two adjacent elements of the string. Find the minimum value of f(s) that can be achieved if at most k operations are allowed. Each test contains multiple test cases. The first line contains the number of test cases t ( 1 <= t <= 10^5 ). Description of the test cases follows. First line of each test case contains two integers n and k ( 2 <= n <= 10^5 , 0 <= k <= 10^9 ) -- the length of the string and the maximum number of operations allowed. The second line of each test case contains the binary string s of length n , consisting of only zeros and ones. It is also given that sum of n over all the test cases doesn't exceed 10^5 . For each test case, print the minimum value of f(s) you can obtain with at most k operations. "...