F1 Score

Compute the F1 score, the harmonic mean of precision and recall.

Implement solve(precision, recall).

Returns. Return a float in $[0,1][0,1]$. If precision and recall are both $00$ return 0.0.

Examples

Example 1

Input:

solve(0.5, 0.5)

Output:

0.5

Example 2

Input:

solve(1.0, 0.25)

Output:

0.4

Example 3

Input:

solve(0.0, 0.0)

Output:

0.0