program carz;
const
  maxtin=1000000;
var
  i,j,s:longint;
  min,t:real;
  f,v:array[0..1000]of real;
procedure init;
begin
  assign(input,'carz.in');
  reset(input);
  assign(output,'carz.out');
  rewrite(output);
  read(s,t);
  for i:=0 to s do
  begin
    if i<=10  then v[i]:=100
    else if i<=20 then v[i]:=90
    else if i<=30 then v[i]:=80
    else if i<=40 then v[i]:=75
    else if i<=s then v[i]:=70
  end;
  for i:=1 to s do
    f[i]:=maxtin;
  t:=t/60
end;

procedure dp;
begin
  for i:=1 to s do
    for j:=1 to i do
      if i-j>=0 then
        if f[i]>f[i-j]+t+j/v[j] then
          f[i]:=f[i-j]+t+j/v[j]
end;

procedure print;
begin
  min:=f[s]-t;
  writeln(min:0:2);
  close(input);
  close(output)
end;

begin
  init;
  dp;
  print
end.