Untitled

#include <iostream>
#include <string>
#include <fstream>
#include <iomanip>
using namespace std;
float ploshad(float a, float b, float h)
{
	float d =  1.0 / 3.0 * a * b * h;
	return d;
}
int main()
{

	float a, b, s, h;
	ifstream in("input.txt");
	ofstream out("output.txt");
	in >> a >> b >> h;
	out << std::fixed << std::showpoint;
	out << std::setprecision(2);
	out << ploshad(a,b,h) << std::endl;
}