program Untitled;
var
   n, a, p, k, rj, i : longint;
begin
     readln ( n );
     read ( a );
     p := a;
     k := a;
     rj := 0;
     for i := 2 to n - 1 do
     begin
          read ( a );
          if a <= p then
          begin
               if p - k > rj then rj := p - k;
               k := a;
          end;
          p := a;
     end;
     read ( a );
     if a <= p then
     begin
          if p - k > rj then rj := p - k;
     end;
     if a > p then
     begin
          if a - k > rj then rj := a - k;
     end;
     readln;
     writeln ( rj );
readln;
end.