#include<cstdio>
#include<iostream>
#include<algorithm>
#include<cstdlib>
#define inf (1<<30)
using namespace std;
double f[10005];
int s,t;
int main()
{
	freopen("carz.in","r",stdin);
	freopen("carz.out","w",stdout);
	int i;
	scanf("%d%d",&s,&t);
	for(i=1;i<=s;i+=1)
	{
		f[i]=double(inf);
//		printf("%.2f\n",f[i]);
		if(i<=10)
		{
			if(f[i]>double((double)i/(double)100))
			f[i]=double((double)i/(double)100);
		}
		else
		{
			if(f[i]>f[i-10]+double((double)t/(double)60)+double((double)10/(double)100))
			f[i]=f[i-10]+double((double)t/(double)60)+double((double)10/(double)100);
		}
		if(i<=20)
		{
			if(f[i]>double((double)i/(double)90))
			f[i]=double((double)i/(double)90);
		}
		else
		{
			if(f[i]>f[i-20]+double((double)t/(double)60)+double((double)20/(double)90))
			f[i]=f[i-20]+double((double)t/(double)60)+double((double)20/(double)90);
		}
		if(i<=30)
		{
			if(f[i]>double((double)i/(double)80))
			f[i]=double((double)i/(double)80);
		}
		else
		{
			if(f[i]>f[i-30]+double((double)t/(double)60)+double((double)30/(double)80))
			f[i]=f[i-30]+double((double)t/(double)60)+double((double)30/(double)80);
		}
		if(i<=40)
		{
			if(f[i]>double((double)i/(double)75))
			f[i]=double((double)i/(double)75);
		}
		else
		{
			if(f[i]>f[i-40]+double((double)t/(double)60)+double((double)40/(double)75))
			f[i]=f[i-40]+double((double)t/(double)60)+double((double)40/(double)75);
		}
		if(double((double)(i)/double(70))<f[i])f[i]=double((double)(i)/double(70));
	}
	printf("%.2f\n",f[s]);
	return 0;
}