Problems

# Vector length

# Vector length

Find the length of the vector.

#### Input

Four integers `x`

, _{1}`y`

, _{1}`x`

, _{2}`y`

- the coordinates of the beginning and end of the vector, respectively. All input data do not exceed _{2}**10000** by absolute value.

#### Output

Print the length of the given vector with **6** digits after the decimal point.

Input example #1

1 1 2 2

Output example #1

1.414214