program groupa;
var
  n,a,b,i,sum:longint;
  sz:array[1..50]of longint;
begin
  assign(input,'groupa.in');
  assign(output,'groupa.out');
  reset(input);
  rewrite(output);
  readln(n);
  for i:=1 to n do
    read(sz[i]);
  readln;
  readln(a,b);
  sum:=0;
  for i:=1 to n do
    sum:=sum+sz[i];
  if (sum<a*n)or(sum>b*n) then writeln(-1) else begin
    sum:=0;
    for i:=1 to n do
      if sz[i]>b then sum:=sum+sz[i]-b;
    writeln(sum);
  end;
  close(input);
  close(output);
end.