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

Solution (in CPP):

Solution:
#include<iostream>
#include<cstdio>
#include<cmath>
using namespace std;
int main(){
double x1,x2,y1,y2;
cin >>x1 >>y1 >>x2 >>y2;
double d=sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));
printf("%lf\n",d);
return 0;
}