#include<bits/stdc++.h>
using namespace std;
int main(){
    float x,y,z,a,b,c,h;
    cin>>a>>b>>c;
    h=a*8.5+c*6.2+b*5.6;
    printf("%.1f",h);
}
/**************************************************************
	Problem: 1610
	User: toughuatao1
	Language: C++
	Result: Accepted
	Time:7 ms
	Memory:2072 kb
****************************************************************/