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<cstdio>
#include<cmath>
int main(){
  double x1,y1,x2,y2;
  scanf("%lf %lf %lf %lf",&x1,&y1,&x2,&y2);
  printf("%.7f\n",sqrt(pow(x2-x1,2)+pow(y2-y1,2)));//7f浮動小数点数,pow=sqrt
}