#include <iostream>
#include <math.h>
#include <stdio.h>

int main() {
	double x1, x2, y1, y2;
	scanf("%lf %lf %lf %lf", &x1, &y1, &x2, &y2);
	printf("%.8lf\n", sqrt((x2-x1)*(x2-x1) + (y2-y1)*(y2-y1)));
	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 <iostream>
#include <math.h>
#include <stdio.h>

int main() {
	double x1, x2, y1, y2;
	scanf("%lf %lf %lf %lf", &x1, &y1, &x2, &y2);
	printf("%.8lf\n", sqrt((x2-x1)*(x2-x1) + (y2-y1)*(y2-y1)));
	return 0;
}

```