#include<stdio.h>
double f[10001];

double _min(double aa,double b){if(aa<b)return aa; return b;}

int main(){
	freopen("caze.in","r",stdin);
	freopen("caze.out","w",stdout);
	int s,i,j;
	double t,g;
	scanf("%d%lf",&s,&t);
	t/=60;
	double a[4]={75,100,90,80};
	for(i=10;i<=s;i+=10){
		if(i>40)f[i]=double(i)/double(70);
		else f[i]=double(i)/a[i/10%4];
		for(j=10;j<i;j+=10){
			if(i-j>40)g=70;
			else g=a[(i-j)/10%4];
			f[i]=_min(f[i],f[j]+t+double(i-j)/g);
		}
	}
	printf("%.2lf",f[s]);
	return 0;
}