PROGRAMMING:Two point distance

Enter the coordinates of two points, your task is to calculate the geometric distance between two points
Is it simple?
###Input format:
There are several groups of test data, each line has four integers, x1, Y1, X2, Y2, which represent two-point coordinates
###Output format:
A real number (double), representing the distance between two points, the results retain 3 significant digits
###Input example:
```in
2 3 1 3
2 3 1 4
```
###Output example:
```out
one
one point four one four
```







answer：If there is no answer, please comment