#include <cstdio>
using namespace std;

int speed10[1001]={0,100,90,80,75,70};
double f10[1001]={0};

int main(void)
{
	freopen("carz.in","r",stdin);
	freopen("carz.out","w",stdout);
	int i,j,s;
	double t,temp;
	scanf("%d %lf\n",&s,&t);
	s/=10;
	t/=60;
	for (i=6;i<=s;i++)
		speed10[i]=70;
	f10[0]=-t;
	for (i=1;i<=s;i++)
	{
		f10[i]=100000000;
		for (j=i-1;j>=0;j--)
		{
			temp=f10[j]+double((i-j)*10)/double(speed10[i-j])+t;
			if (temp<f10[i])
			{
				f10[i]=temp;
			}
		}
	}
	printf("%.2lf\n",f10[s]);
	fclose(stdin);
	fclose(stdout);
	return(0);
}