PROGRAMMING:seek π Approximate value of
Input precision e, using Gregory formula π The absolute value of the last term is less than E. It is required to define and call funpi (E) π The approximate value of.
$$\frac{\pi }{4}=1-\frac{1}{3}+\frac{1}{5}-\frac{1}{7}+...$$
###Input format:
The input gives the precision E in one line.
###Output format:
For each set of inputs, output in one line π The approximate value of.
###Input example:
```in
zero point zero zero zero one
```
###Output example:
```out
pi = 3.141793
```
answer：If there is no answer, please comment
$$\frac{\pi }{4}=1-\frac{1}{3}+\frac{1}{5}-\frac{1}{7}+...$$
###Input format:
The input gives the precision E in one line.
###Output format:
For each set of inputs, output in one line π The approximate value of.
###Input example:
```in
zero point zero zero zero one
```
###Output example:
```out
pi = 3.141793
```
answer：If there is no answer, please comment