program carz;
var
f:array[1..10000]of real;
b:array[1..10000]of integer;
i,j,k,m,n,max,s,t:longint;
function min(x,y:real):real;
begin
if x<y then min:=x else min:=y;
end;
begin
assign(input,'carz.in');reset(input);assign(output,'carz.out');rewrite(output);
read(s,t);
for i:=1 to s do
begin
if i<=10 then b[i]:=100;
if (i>10)and(i<=20) then b[i]:=90;
if (i>20)and(i<=30) then b[i]:=80;
if (i>30)and(i<=40) then b[i]:=75;
if i>40 then b[i]:=70;
end;
f[s div 10]:=s/b[s];
f[1]:=0.1;
for i:=1 to s div 10 do
f[i]:=i*10/b[i*10];
for i:=1 to s div 10 do
begin
for j:=i-1 downto 1 do
f[i]:=min(f[i],f[i-j]+j*10/b[j*10]+t/60) ;
end;
writeln(f[s div 10]:0:2);
close(input);close(output);
end.