#include <bits/stdc++.h>

using namespace std;

int main(void){
  double a, b, c, d;
  scanf("%lf %lf %lf %lf", &a, &b, &c, &d);
  printf("%lf\n", sqrt((a - c)*(a - c) + (b - d)*(b - d)));
  return 0;
}


### Prompt

In Cpp, your task is to solve the following problem:

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

### Response

```cpp
#include <bits/stdc++.h>

using namespace std;

int main(void){
  double a, b, c, d;
  scanf("%lf %lf %lf %lf", &a, &b, &c, &d);
  printf("%lf\n", sqrt((a - c)*(a - c) + (b - d)*(b - d)));
  return 0;
}


```