class Punkt
{
int x;
int y;
Punkt(int x,int y)
{
this.x=x;
this.y=y;
}
void wypisz()
{
System.out.println("("+x+","+y+")");
}
double odl(Punkt P)
{
return Math.sqrt(((x-P.x)*(x-P.x))+((y-P.y)*(y-P.y)));
}
}
class Trojkat
{
Punkt A;
Punkt B;
Punkt C;
Trojkat(Punkt A,Punkt B,Punkt C)
{
if(((A.odl(B)+A.odl(C)>B.odl(C))&&(A.odl(B)+B.odl(C)>A.odl(C))&&(B.odl(C)+A.odl(C)>A.odl(B))))
{
this.A=A;
this.B=B;
this.C=C;
}
else 
System.out.println("nie mozna zbudowac trojkata");
}
void czyRownoboczny()
{
if((A.odl(B)==A.odl(C))&&(A.odl(B)==B.odl(C))&&(B.odl(C)==A.odl(C)))
System.out.println("rownoboczny");
else
System.out.println("nie rownoboczny");
}
void wypisz()
{
System.out.println("A("+A.x+","+A.y+")"+"B("+B.x+","+B.y+")C("+C.x+","+C.y+")");
System.out.println(A.odl(B)+","+A.odl(C)+","+B.odl(C));
}
void wypisz1()
{System.out.print("A");
A.wypisz();
System.out.print("B");
B.wypisz();
System.out.print("C");
C.wypisz();
}
void proste()
{
 double a=((double)(A.y-B.y)/(A.x-B.x));
 double b=(A.y-a*A.x);
 System.out.println("y="+a+"*x+"+b);
 
}
double pole()
{
double p=(A.odl(B)+A.odl(C)+B.odl(C))/2;
return Math.sqrt(p*(p-A.odl(B))*(p-A.odl(C))*(p-B.odl(C)));
}
}
class pr
{
public static void main(String[]args)
{
Punkt A=new Punkt(2,1);
Punkt B=new Punkt(5,5);
Punkt C=new Punkt(9,2);
Punkt D=new Punkt(8,7);
Trojkat T=new Trojkat(A,B,C);
Trojkat T1=new Trojkat(A,C,D);
System.out.println(roznica(T,T1));
wierzch(T,A);
int a=3;
int b=15;
suma(a,b);
//T.czyRownoboczny();
//T.wypisz();
//System.out.println(A.odl(B));
//T.proste();
}
static double roznica(Trojkat T,Trojkat T1)
{
return T.pole()-T1.pole();
}
static void wierzch(Trojkat T,Punkt P)
{
 if(P==A||P==B||P==C)
 System.out.println("jets wierzcholkiem");
 else
 System.out.println("nie jest wierzhclkeim");
}
static double suma(int a,int b)
{ double suma=0;
for(int i=a;i<=b;i++)
{
 suma=suma+b/(i*a);
 }
 System.out.println(suma);
 }
 }