program ex(f1,f2);
 var
  s,p,m,n,k,l,i,j,ss,ans:longint;
  f1,f2:text;
 procedure find(s,v,t:integer);
  var
   i,j,k:integer;
  begin
   if s>=ss then begin if t<ans then ans:=t; end
   else begin
   if v=p then find (s+10,v-10,t+10)
   else begin
         if v-1<0 then find(s+1,0,t+1) else find(s+1,v-1,t+1);
         if v+2<=p then find(s+5,v+2,t+1);
         if v+5<=p then find(s+10,v+5,t+1);
        end;
         end;
   end;

 begin
  assign(f1,'goat.in'); reset(f1);
  assign(f2,'goat.out'); rewrite(f2);
  ans:=99999999;
  readln(f1,ss,p);
  find(0,0,0);
  writeln(f2,ans);
  close(f1);
  close(f2);
 end.