#include <iomanip>

int main() {
    int n;
    std::cin >> n;
    
    double max_area = 0.0;
    
    for (int i = 0; i < n; ++i) {
        int a, b, h;
        std::cin >> a >> b >> h;
        double area = (a + b) * h / 2.0;
        if (area > max_area) {
            max_area = area;
        }
    }
    
    std::cout << std::fixed << std::setprecision(1) << max_area << std::endl;
    
    return 0;
}
/**************************************************************
	Problem: 1330
	User: zhenghaoxuan
	Language: C
	Result: Compile Error
****************************************************************/