PROGRAMMING:Husky looking for a pet dog

Husky has a pet dog named Jinmao. Today, Jinmao went out to play and didn't go home. Husky is very anxious and decides to find Jinmao. It is known that Husky's position is x1, Y1. The position of golden hair is X2, Y2. Husky's velocity is v; Ask husky the fastest time to find golden hair（ Keep the answer to 2 decimal places)
###Input format:
There are several groups of test data, input five integers x1, Y1, X2, Y2, V;
###Output format:
Output the fastest time to find golden hair（ Keep the answer to 2 decimal places.
###Input example:
```in
1 0 2 0 1
```
###Output example:
The corresponding output is given here. For example:
```out
one
```







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