#include<stdio.h>

#include<math.h>

int main()

{

double a,b,c,s,area;

scanf("%lf%lf%lf",&a,&b,&c); //输入时double类型必须用%lf，float才用%f

//a=11113.67;

//b=11115.43;

//c=11116.21;

s=(a+b+c)/2;

area=sqrt(s(s-a)(s-b)*(s-c));

printf("a=%g,b=%g,c=%g\n",a,b,c);

printf("area=%g\n\n",area);

return 0;

}