#include <iostream>
#include <iomanip>
int main() {
    double x, y, z;
    // 读取输入的三种水果的斤数
    std::cin >> x >> y >> z;
    // 定义三种水果的单价
    const double applePrice = 8.5;
    const double pearPrice = 5.6;
    const double orangePrice = 6.2;
    // 计算总金额
    double totalCost = applePrice * x + pearPrice * y + orangePrice * z;
    // 输出结果，保留一位小数
    std::cout << std::fixed << std::setprecision(1) << totalCost;
    return 0;
}
    
/**************************************************************
	Problem: 1610
	User: fuyijun
	Language: C++
	Result: Accepted
	Time:6 ms
	Memory:2072 kb
****************************************************************/