#include <cstdio>
#include <cmath>
int main() {
	double a, b, c, d;
	scanf("%lf %lf %lf %lf", &a, &b, &c, &d);
	printf("%f\n", sqrt(pow(c - a, 2) + pow(d - b, 2)));
}
### Prompt

Develop a solution in Cpp to the problem described below:

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 a, b, c, d;
	scanf("%lf %lf %lf %lf", &a, &b, &c, &d);
	printf("%f\n", sqrt(pow(c - a, 2) + pow(d - b, 2)));
}
```