// KZ's
#include <cstdio>
double min(double a,double b) {
	return a<b?a:b;
}
int main() {
	freopen("carz.in","r",stdin);
	freopen("carz.out","w",stdout);
	int s;
	double f[1003]={0},t;
	double spd[1003]={1,10,9,8,7.5,7};
	scanf("%d%lf",&s,&t);
	s=s/10+1;
	t/=60;
	for (int i=1;i<6;i++) {
		f[i]=i/spd[i];
		for (int j=1;j<=i;j++)
			f[i]=min(f[i-j]+min(j/spd[j],f[j])+t,f[i]);
	}
	for (int i=6;i<s;i++) {
		spd[i]=7;
		f[i]=i/spd[i];
		for (int j=1;j<=i;j++)
			f[i]=min(f[i-j]+min(j/spd[j],f[j])+t,f[i]);
	}
	printf("%.2lf\n",f[s-1]);
	return 0;
}
// UBWH