Program Pr1;uses crt;var a,b,c,p,s:real;beginclrscr;readln(a,b,c);p:=(a+b+c)/2;s:=(p-a)*(p-b)*(p-c);s:=s*p;s:=sqrt(s);writeln(s);end.
Program Pr1;
uses crt;
var a,b,c,p,s:real;
begin
clrscr;
readln(a,b,c);
p:=(a+b+c)/2;
s:=(p-a)*(p-b)*(p-c);
s:=s*p;
s:=sqrt(s);
writeln(s);
end.