#include <bits/stdc++.h>
using namespace std;
double n,x,cnt=9.0;
int main() {
	freopen("taxi.in","r",stdin);
	freopen("taxi.out","w",stdout);
	cin>>n>>x;
	if(x==1) {
		if(n>3&&n<=6) {
			cnt=cnt+(n-3)*1.5;
		}if(n>6) {
			cnt=cnt+3*1.5+(n-6)*2.25;
		}
	}
	else {
		if(n>3&&n<=6) {
			cnt=cnt+(n-3)*1.75;
		}
		if(n>6) {
			cnt=cnt+3*1.75+(n-6)*2.5;
		}
	}
	cout<<fixed<<setprecision(2)<<cnt<<endl;
	return 0;
}