1064

 1 #include <iostream>

 2 #include <iomanip>

 3 #include <cmath>

 4 using namespace std;

 5 int main()

 6 {

 7     int n,m,x,y;

 8     while(cin>>n>>m>>x>>y)

 9     {

10         cout <<setiosflags(ios::fixed)<<setprecision(2)<<sqrt((x-n)*(x-n)+(y-m)*(y-m))<< endl ;

11     }

12     return 0;

13 }