Distance

Write a program which calculates the distance between two points P1(x1, y1) and P2(x2, y2).

Input

Four real numbers x1, y1, x2 and y2 are given in a line.

Output

Print the distance in real number. The output should not contain an absolute error greater than 10-4.

Example

Input

0 0 1 1

Output

1.41421356

inputFormat

Input

Four real numbers x1, y1, x2 and y2 are given in a line.

outputFormat

Output

Print the distance in real number. The output should not contain an absolute error greater than 10-4.

Example

Input

0 0 1 1

Output

1.41421356

样例

0 0 1 1

1.41421356