#include<cstdio>

#define eps 1e-5

using namespace std;

int n;
double v[10010],f[10010],t;

double MIN(double a,double b)
{
	if(a-b>eps)	return b;
	return a;
}

int main()
{
	freopen("carz.in","r",stdin);
	freopen("carz.out","w",stdout);
	scanf("%d%lf",&n,&t);
	t/=(double)60;
	for(int i=0;i<=n;i++)	f[i]=1000000000.0;
	f[0]=0.0;
	v[10]=100.0;v[20]=90.0;v[30]=80.0;v[40]=75.0;
	for(int i=50;i<=n;i+=10)	
		v[i]=70.0;
	for(int i=10;i<=n;i+=10){
		f[i]=i/v[i];
		for(int j=10;j<i;j+=10){
			f[i]=MIN(f[i],f[j]+t+((i-j)/v[i-j]));
		}
	}
	printf("%.2lf",f[n]);
	getchar();getchar();
	return 0;
}