var f,g:text;
    q,p,s,n,m,i:longint;
begin
  assign(f,'stramosi.in'); reset(f);
  assign(g,'stramosi.out'); rewrite(g);
  read(f,n,m);
  for i:=1 to m do
    begin
      read(f,q,p);
      s:=q-p;
      if s<0 then s:=0;
      writeln(g,s);
    end;
  close(f); close(g);
end.