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CF2176B.Optimal Shifts
Optimal Shifts
You are given a binary string , containing at least one 1. You want to obtain a binary string of the same length, consisting only of 1s. To do this, you can perform the following operation any number of times:
Choose a number () and consider the string as a cyclic right shift of the string by , or, more formally, $t = s_{n - d + 1} \ldots s_{n}s_{1} \ldots s_{n - d}$. After that, for all for which , perform . The described operation costs coins, where is the chosen shift amount.
Note that the positions in the string , where initially , remain equal to even if .
You need to determine the minimum number of coins that can be spent so that the string consists only of 1s after all operations.
Input
Each test contains multiple test cases. The first line contains the number of test cases (). The description of the test cases follows.
The first line of each test case contains the number () — the size of the given binary string.
The second line of each test case contains a binary string of length , each element of which is either 0 or 1.
It is guaranteed that at least one character in each string is equal to 1.
It is guaranteed that the sum of across all test cases does not exceed .
Output
For each test case, output the answer to it — the minimum possible number of coins that you can spend to make all characters in the string equal to 1.
Note
Consider the third example, where "0110". In this case, it is optimal to choose , then "1001". After that, at positions and , will be replaced with 1, resulting in the string consisting of all ones. Note that the cost of this operation is .
Samples
5
1
1
3
101
4
0110
11
10101010100
2
11
0
1
2
2
0
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