#include <iostream>
#include <cmath>
using namespace std;
int main() {
int x1,y1,x2,y2;
cout<<"x1=";
cin>>x1;
cout<<"y1=";
cin>>y1;
cout<<"x2=";
cin>>x2;
cout<<"y2=";
cin>>y2;
double dist = sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));
cout<<"dist = "<<dist<<endl;
return 0 ;
}