#include<stdio.h>
#include<cmath>
using namespace std;

int main(){
    double x1,y1,x2,y2,x,y;
    scanf("%lf %lf %lf %lf", &x1,&y1,&x2,&y2);
    x = x1-x2;
    y = y1-y2;
    printf("%f\n", sqrt(x*x+y*y));
}

### Prompt

Please create a solution in CPP 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<stdio.h>
#include<cmath>
using namespace std;

int main(){
    double x1,y1,x2,y2,x,y;
    scanf("%lf %lf %lf %lf", &x1,&y1,&x2,&y2);
    x = x1-x2;
    y = y1-y2;
    printf("%f\n", sqrt(x*x+y*y));
}

```