Fixed-size array

Given an array of integers:

a = [0, 2, 7, 4, 2, 1]

The procedure below performs some calculations with the array:

r = 0
for (i = 0; i < len(a); i = i + 1):
    if a[i] < len(a) then:
        r = r + a[i]

Print the final value of $r$ after these calculations in the answer field below. The output should be an integer number.

Recall that len(a) returns the length of the array a.