var n,a,b,i,h:longint;
    l:array[1..300] of longint;
begin
  readln(n);
  for i:=1 to n do
    read(l[i]);
  read(a,b);
  for i:=a to b do
    h:=h+l[i];
  writeln(h);
end.
/**************************************************************
	Problem: 2088
	User: admin
	Language: Pascal
	Result: Wrong Answer
****************************************************************/