Problem 37: Sum of a Given Range

An integer N is given on the first line, and N integers separated by single spaces are given on the second line. Integers L and R are given on the third line, separated by a single space.

Output, on one line, the sum of the elements from the L-th to the R-th (inclusive) in the sequence. Count the first element as the 1st.

For example, if the sequence is 1 2 3 4 5 and L=2, R=4, then 2 + 3 + 4 = 9, so output 9.

Constraints

1 ≤ N ≤ 100, 1 ≤ L ≤ R ≤ N, 0 ≤ each element ≤ 1000

Input example 1

5
1 2 3 4 5
2 4

Output example 1

9

Input example 2

3
10 20 30
1 3

Output example 2

60