Statement
Pillow CPU repeatedly transforms a positive integer by the following process.
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If the current value is , terminate the process.
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Choose an integer uniformly at random from through . This step takes second.
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If is divisible by , replace by . Otherwise, leave unchanged.
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Return to step .
Given the initial integer , compute the expected time until the process terminates. The elapsed time depends only on the number of times step is executed.
Input
The input is given from Standard Input in the following format:
Output
For each test case, print the expected time until the process terminates, rounded to exactly two digits after the decimal point.
Constraints
- .
- .
Subtasks
Samples
When , the process terminates immediately without making any choice, so the answer is .