#include <cstdio>
#include <cmath>
int main(){
	double x, y, z, w;
	scanf("%lf%lf%lf%lf", &x, &y, &z, &w);
	printf("%.8f", sqrt((x-z)*(x-z)+(y-w)*(y-w)));
	return 0;
}

### Prompt

Create a solution in cpp for 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 <cstdio>
#include <cmath>
int main(){
	double x, y, z, w;
	scanf("%lf%lf%lf%lf", &x, &y, &z, &w);
	printf("%.8f", sqrt((x-z)*(x-z)+(y-w)*(y-w)));
	return 0;
}

```