Given and , and , find when .

#### Input Specification

The first line will contain three integers, .

#### Output Specification

Output a value of where . Your value of will be considered correct if .

#### Sample Input

`1 1 20`

#### Sample Output

`19.4417867`

Given and , and , find when .

The first line will contain three integers, .

Output a value of where . Your value of will be considered correct if .

`1 1 20`

`19.4417867`

## Comments