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A top-secret algorithmic research facility has decided to up its security by |
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hiring guards to keep watch over the premises. After all, they don't want |
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anyone sneaking in and learning the answers to questions such as "does P = |
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NP?" and "what are the solutions to the 2016 Facebook Hacker Cup problems?". |
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When viewed from above, the facility can be modeled as a grid **G** with 2 |
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rows and **N** columns. The **j**th cell in the **i**th row is either empty |
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(represented by **Gi,j** = ".") or occupied by a building (**Gi,j** = "X"), |
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and the grid includes at least one empty cell. |
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Guards may be potentially stationed in any of the empty cells. A guard can see |
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not only their own cell, but also all contiguous empty cells in each of the 4 |
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compass directions (up, down, left, and right) until the edge of the grid or a |
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building. For example, in the grid below, the guard ("G") can see every cell |
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marked with an asterisk ("*"): |
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.*.X.X.. |
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*G*****X |
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What is the minimum number of guards required such that every empty cell in |
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the grid can be seen by at least one of them? |
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### Input |
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Input begins with an integer **T**, the number of facilities that need |
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guarding. For each facility, there is first a line containing the integer |
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**N**. The next line contains the grid cells **G1,1** to **G1,N** in order. |
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The third line contains the grid cells **G2,1** to **G2,N** in order. |
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### Output |
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For the **i**th facility, print a line containing "Case #**i**: " followed by |
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the number of guards required to guard the facility. |
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### Constraints |
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1 ≤ **T** ≤ 200 |
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1 ≤ **N** ≤ 1,000 |
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### Explanation of Sample |
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In the first case, one solution is to place three guards as follows: |
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.G.X.XG. |
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....G..X |
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