#include<bits/stdc++.h>
#define rep(i,n)for(int i=0;i<n;i++)
using namespace std;

int main() {
	double x1, y1, x2, y2; cin >> x1 >> y1 >> x2 >> y2;
	x2 -= x1; y2 -= y1;
	printf("%.7lf\n", sqrt(x2*x2 + y2*y2));
}
### 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<bits/stdc++.h>
#define rep(i,n)for(int i=0;i<n;i++)
using namespace std;

int main() {
	double x1, y1, x2, y2; cin >> x1 >> y1 >> x2 >> y2;
	x2 -= x1; y2 -= y1;
	printf("%.7lf\n", sqrt(x2*x2 + y2*y2));
}
```