#include <bits/stdc++.h>
using namespace std;
int x[24],y[24];
int main()
{
    for(int i=1;i<=3;i++)
    {
        cin>>x[i]>>y[i];
    }
    int a=sqrt(abs((x[1]-x[2]))*abs((x[1]-x[2]))+abs((y[1]-y[2]))*abs((y[1]-y[2])));
    int b=sqrt(abs((x[3]-x[2]))*abs((x[3]-x[2]))+abs((y[3]-y[2]))*abs((y[3]-y[2])));
    int c=sqrt(abs((x[3]-x[1]))*abs((x[3]-x[1]))+abs((y[3]-y[1]))*abs((y[3]-y[1])));
    int s=(a+b+c)/2;
    cout<<sqrt(s*abs(s-a)*abs(s-b)*abs(s-c));
    return 0;
}