#include <bits/stdc++.h> using namespace std; int main(){ double x1,y1,x2,y2,x3,y3; cin>>x1>>y1>>x2>>y2>>x3>>y3; double m,n,e,p,s; m=sqrt((x1-x2)(x1-x2)+(y1-y2)(y1-y2)); n=sqrt((x1-x3)(x1-x3)+(y1-y3)(y1-y3)); e=sqrt((x3-x2)(x3-x2)+(y3-y2)(y3-y2)); p=(m+n+e)/2; s=sqrt(p*(p-m)(p-n)(p-e)); cout<<fixed<<setprecision(2)<<s; return 0; }