Background

This problem is an exercise on prefix sums. Please solve this problem using prefix sums.

Please use C++, and use scanf() instead of std::cin.

Description

Given an integer sequence, find the sum from the $l$-th term to the $r$-th term.

Input

The input consists of $3$ lines:

• Line 1: A positive integer $n$, the length of the integer sequence.
• Line 2: $n$ integers $a_1, a_2, \cdots, a_n$, representing the integer sequence.
• Line 3: Two positive integers $l$ and $r$, indicating that we require the sum from the $l$-th to the $r$-th term.

Output

Output one line with a single integer $s$, the sum from the $l$-th to the $r$-th term in the integer sequence.

6
178 24 16 -19 52 1
2 4

21

Hint

For test cases #1 to #10, it is guaranteed that $1 \le n \le 6000$, $-10^5 \le a_i \le 10^5$, and $1 \le l \le r \le n$.

For test case #11, $n = 10^6$ and $-10^5 \le a_i \le 10^5$.