hdoj2001

 #include<iostream>#include<cmath>using namespace std;int main(){    double x1,y1,x2,y2;    cout.precision(2);    while( cin >> x1 >> y1 >> x2 >> y2)    {           cout << fixed << sqrt(pow((x1-x2),2)+pow((y1-y2),2)) << endl;           }    system("pause");    }