#include<bits/stdc++.h>
using namespace std;


int main(){
    double x1,x2,y1,y2;
    cin >> x1 >> x2 >> y1 >> y2;
    double ans;
    ans=(x1-y1)*(x1-y1)+(x2-y2)*(x2-y2);
    printf("%.10lf\n",sqrt(ans));



}

### 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>
using namespace std;


int main(){
    double x1,x2,y1,y2;
    cin >> x1 >> x2 >> y1 >> y2;
    double ans;
    ans=(x1-y1)*(x1-y1)+(x2-y2)*(x2-y2);
    printf("%.10lf\n",sqrt(ans));



}

```