#include<cstdio>
#include<cstring>
using namespace std;
int s,v[1001],i,j;
double t,f[1001];
double min(double a,double b){return a<b?a:b;}
int Main()
{
	freopen("carz.in","r",stdin);freopen("carz.out","w",stdout);
	scanf("%d%lf",&s,&t);
	s/=10;t/=60;
	v[1]=100;v[2]=90;
	v[3]=80;v[4]=75;
	for(i=5;i<=s;i++)v[i]=70;
	f[0]=-t;
	for(i=1;i<=s;i++)
	{
		f[i]=0x7fffffff;
		for(j=i-1;j>=0;j--)
		{
			double tmp=double((i-j)*10.0)/double(v[i-j]);
			f[i]=min(f[i],f[j]+tmp+t);
		}
	}
	printf("%.2lf\n",f[s]);
	return 0;
}
int main(){;}
int syy=Main();