#include<cstdio>
#include<algorithm>
using namespace std;
const double a=(double)2/9,b=(double)3/8,c=(double)8/15;
double f[10000]={0};
int s,t;
int main(){
	freopen("carz.in","r",stdin);
	freopen("carz.out","w",stdout);
	scanf("%d%d",&s,&t);
	s/=10;
	double tt=(double)t/60;
	f[0]=0;
	f[1]=0.1;
	f[2]=min(f[1]+f[1]+tt,a);
	f[3]=min(f[1]+f[2]+tt,b);
	f[4]=min(f[1]+f[3]+tt,c);
	for(int i=5;i<=s;i++){
		double maxx=(double)i/7;
		for(int j=1;j<=4&&j<=i-j;j++){
			if(f[j]+f[i-j]+tt<maxx)
				maxx=f[j]+f[i-j]+tt;
		}
		f[i]=maxx;
	}
	printf("%.2f",f[s]);
}