PROGRAMMING:Finding the spherical distance between two points on the equator
It is known that the equatorial radius of the earth is 6378.137 km, and the longitude (in degrees) of two points on the equator of the eastern hemisphere is known. A program is written to calculate the spherical distance between the two points. All real numbers are required to use double type, and the approximate value of PI is 3.141592653589793.
Tip: the spherical distance between two points on the equator is the length of the inferior arc between two points on the equator.
###Input format:
Enter two non negative real numbers representing longitude on a line, separated by spaces.
###Output format:
Output the value of spherical distance, keep 3 decimal places, and finally wrap.
###Input example:
```in
63.2 136.9
```
###Output example:
```out
eight thousand two hundred and four point two four six
```
answer：If there is no answer, please comment
Tip: the spherical distance between two points on the equator is the length of the inferior arc between two points on the equator.
###Input format:
Enter two non negative real numbers representing longitude on a line, separated by spaces.
###Output format:
Output the value of spherical distance, keep 3 decimal places, and finally wrap.
###Input example:
```in
63.2 136.9
```
###Output example:
```out
eight thousand two hundred and four point two four six
```
answer：If there is no answer, please comment