PROGRAMMING:Using Gregory formula to get pI value of given precision
This problem requires programming to calculate the sequence part and $$4 * (1 - 1 / 3 + 1 / 5 - 1 / 7 +...) $$, until the absolute value of the last term is less than the given precision 'EPS'.
###Input format:
Enter to give a positive real number 'EPS' on a line.
###Output format:
In one line, output the value of partial sum 'Pi' in the format of 'pi = Pi', which is accurate to four decimal places. It is ensured that the input data and calculation results are within the double precision range.
###Input sample 1:
```in
zero point zero zero zero one
```
###Output sample 1:
```out
Pi = 3.1418
```
###Input sample 2:
```in
zero point two
```
###Output sample 2:
```out
Pi = 2.8952
```
answer：If there is no answer, please comment
###Input format:
Enter to give a positive real number 'EPS' on a line.
###Output format:
In one line, output the value of partial sum 'Pi' in the format of 'pi = Pi', which is accurate to four decimal places. It is ensured that the input data and calculation results are within the double precision range.
###Input sample 1:
```in
zero point zero zero zero one
```
###Output sample 1:
```out
Pi = 3.1418
```
###Input sample 2:
```in
zero point two
```
###Output sample 2:
```out
Pi = 2.8952
```
answer：If there is no answer, please comment