题目详情 - spiralgrid - 南阳理工学院OJ

ID: 668

远端评测题

2000ms

128MiB

尝试: 0

已通过: 0

难度: (无)

上传者:

Hydro

Xiaod has recently discovered the grid named "spiral grid".
Construct the grid like the following figure. (The grid is actually infinite. The figure is only a small part of it.)

Considering traveling in it, you are free to any cell containing a composite number or 1, but traveling to any cell containing a prime number is disallowed. In addition, traveling from a prime number is disallowed, either. You can travel up, down, left or right, but not diagonally. Write a program to find the length of the shortest path between pairs of nonprime numbers, or report it's impossible.

Input

Each test case is described by a line of input containing two nonprime integer 1 <=x, y<=10,000.

Output

For each test case, display its case number followed by the length of the shortest path or "impossible" (without quotes) in one line.

Sample Input

1 4
9 32
10 12

Sample Output

Case 1: 1
Case 2: 7
Case 3: impossible

HINT

Source

NYOJ

#P1667. spiralgrid

spiralgrid

Input

Output

Sample Input

Sample Output

HINT

Source

统计

状态

开发

支持

#P1667. spiralgrid

spiralgrid

Input

Output

Sample Input

Sample Output

HINT

Source

统计

状态

开发

支持

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