#include<iostream>
#include<fstream>
using namespace std;
int main(){
ifstream input;
ofstream output;
input.open("competition.in");
output.open("competition.out");
int a,b,c;
input>>a>>b>>c;
int oc=a*5+b*10+c*15;
if(oc>600){
    oc=600;
}
if(oc<300){
    oc=200;
}
output<<oc/100<<".";
oc%=100;
output<<oc/10;
oc%=10;
output<<oc;
input.close();
output.close();
return 0;
}