prog-0305a

#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;
    }
}