#include<cstdio>
    #include<iostream>
    using namespace std;
    int S;
    double T;
    double v[1010];
    double f[1010];
    double maxn=0x7ffffff;
    int main()
    {
    	freopen("carz.in","r",stdin);
    	freopen("carz.out","w",stdout);
    	scanf("%d%lf",&S,&T);
    	S/=10;
    	T/=60;
    	v[1]=10;v[2]=9;v[3]=8;v[4]=7.5;
    	for(int i=5;i<=S;i++)
    		v[i]=7;
    	for(int i=1;i<=S;i++) f[i]=maxn;
    	f[0]=0;
    	for(int i=1;i<=S;i++)
    	{
    		for(int j=0;j<i;j++)
    		{
    			if(j==0) f[i]=min(f[i],f[j]+((i-j)/v[i-j]));
    			else f[i]=min(f[i],f[j]+((i-j)/v[i-j]+T));
    		}
    	}
    	printf("%0.2lf",f[S]);
    	return 0;
    }