#include<cstdio>
#include<math.h>

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

Your challenge is to write 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<cstdio>
#include<math.h>

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