#include "stdafx.h"
#include <iostream>
#include <cmath>

using namespace std;
double square_triangle(double, double, double);
int main()
{
	double a, b, c;
	a = 3; b = 4; c = 5;
	try{
		double s = square_triangle(a, b, c);
		cout << s << endl;
	}
	catch (int code)
	{
		if (code==1)
			cerr << "Those are non-triangle sides";
		else
			cerr << "Unknown error";
	}
	return 0;
}

double square_triangle(double x, double y, double z)
{
	if (((x + y) > z) && ((x + z) > y) && ((y + z) > x))
	{
		double p = (x + y + z) / 2.0;
		return sqrt(p*(p - x)*(p - y)*(p - z));
	}
	else
	{
		throw 1;
	}
}