#include <iostream>
#include <stdio.h>
#include <math.h>
using namespace std;
int main() {
  double a,b,c,d;
  cin >> a >> b >> c >> d;
  printf("%f\n",sqrt(pow(c-a,2)+pow(d-b,2)));
  return 0;
}

### Prompt

Please formulate a Cpp solution to 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 <iostream>
#include <stdio.h>
#include <math.h>
using namespace std;
int main() {
  double a,b,c,d;
  cin >> a >> b >> c >> d;
  printf("%f\n",sqrt(pow(c-a,2)+pow(d-b,2)));
  return 0;
}

```