#include <iostream>
#include <cmath>
using namespace std;
int main()
{
double a, b, c, p, arie;
int k;
cout << "Introdu laturile: ";
cin >> a >> b >> c;
cout << "Introdu k: ";
cin >> k;
p = (a + b + c)/2;
arie = sqrt(p*(p - a)*(p - b)*(p - c));
cout << "Sunt necesare " << arie * k << " de grame de seminte";
return 0;
}