Problems
Divisible interval
Divisible interval
You are given an array a of integers a1
, a2
, ..., an
. Find any subarray of this array which sum of elements is exactly divisible by n. That is, find numbers (i, j) (1 ≤ i ≤ j ≤ n) such that the sum (ai
+ ai+1
+ ... + aj
) is exactly divisible by n. If such a pair (i, j) cannot be found, then output the pair (−1, −1) as an answer.
Input
The first line contains the number n (1 ≤ n ≤ 105
) of elements of array a. The next line contains n integers a1
, a2
, ..., an
(0 ≤ ai
≤ 109
).
Output
Print any pair (i, j) (1 ≤ i ≤ j ≤ n) satisfying the condition in one line, or (−1, −1) if there is no such pair.
Explanation
a1
+ a2
+ a3
= 4 + 2 + 4 = 10. The sum is divisible by 5.
Input example #1
5 4 2 4 3 6
Output example #1
1 3