题目描述
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
输入格式
见题面
输出格式
见题面
样例输入
0 0 1 1
样例输出
1.41421356