import java.util.Scanner;

public class Main {
	 
    /**
     * @param args
     */
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		double a = sc.nextDouble();
		double b = sc.nextDouble();
		double c = sc.nextDouble();
		double d = a*8.5 + b*5.6 + c*6.2;
		System.out.println(String.format("%.1f", d));
	}
	public static void printArr(int [] a){
		for (int i = 0 ;i<= a.length - 1 ;i++) {
			System.out.print( a[i] + " ");
		}
	}
}
/**************************************************************
	Problem: 1610
	User: admin
	Language: Java
	Result: Accepted
	Time:716 ms
	Memory:40740 kb
****************************************************************/