program a;
var a:array[1..5,1..4]of real;i,j:integer;s:real;
begin
assign(f,legacy.in);
reseat(f);
readln(f,n,m);
close(f);
k:=0;
for i:=1 to n do
  for j:=1 to n do
   if a[i,j+1]>a[i,j] then
     begin
      a[i,j]:=a[i,j+1];
      k:=a[i,j]
     end;
 for i:=1 to n do
  for j:=1 to n do
   if (a[i,j+1]>a[i,j])and(a[i,j+1]<k) then
     begin
      a[i,j]:=a[i,j+1];
      l:=a[i,j]
     end;
x:=k+l-m;
assign(f,legacy.out);
rewrite(f);
write(f,x);
close(f);






         readln;
  end.