#P1141F1. Same Sum Blocks (Easy)
Same Sum Blocks (Easy)
No submission language available for this problem.
Description
This problem is given in two editions, which differ exclusively in the constraints on the number $n$.
You are given an array of integers $a[1], a[2], \dots, a[n].$ A block is a sequence of contiguous (consecutive) elements $a[l], a[l+1], \dots, a[r]$ ($1 \le l \le r \le n$). Thus, a block is defined by a pair of indices $(l, r)$.
Find a set of blocks $(l_1, r_1), (l_2, r_2), \dots, (l_k, r_k)$ such that:
- They do not intersect (i.e. they are disjoint). Formally, for each pair of blocks $(l_i, r_i)$ and $(l_j, r_j$) where $i \neq j$ either $r_i < l_j$ or $r_j < l_i$.
- For each block the sum of its elements is the same. Formally, $$a[l_1]+a[l_1+1]+\dots+a[r_1]=a[l_2]+a[l_2+1]+\dots+a[r_2]=$$ $$\dots =$$ $$a[l_k]+a[l_k+1]+\dots+a[r_k].$$
- The number of the blocks in the set is maximum. Formally, there does not exist a set of blocks $(l_1', r_1'), (l_2', r_2'), \dots, (l_{k'}', r_{k'}')$ satisfying the above two requirements with $k' > k$.
Write a program to find such a set of blocks.
The first line contains integer $n$ ($1 \le n \le 50$) — the length of the given array. The second line contains the sequence of elements $a[1], a[2], \dots, a[n]$ ($-10^5 \le a_i \le 10^5$).
In the first line print the integer $k$ ($1 \le k \le n$). The following $k$ lines should contain blocks, one per line. In each line print a pair of indices $l_i, r_i$ ($1 \le l_i \le r_i \le n$) — the bounds of the $i$-th block. You can print blocks in any order. If there are multiple answers, print any of them.
Input
The first line contains integer $n$ ($1 \le n \le 50$) — the length of the given array. The second line contains the sequence of elements $a[1], a[2], \dots, a[n]$ ($-10^5 \le a_i \le 10^5$).
Output
In the first line print the integer $k$ ($1 \le k \le n$). The following $k$ lines should contain blocks, one per line. In each line print a pair of indices $l_i, r_i$ ($1 \le l_i \le r_i \le n$) — the bounds of the $i$-th block. You can print blocks in any order. If there are multiple answers, print any of them.
Samples
7
4 1 2 2 1 5 3
3
7 7
2 3
4 5
11
-5 -4 -3 -2 -1 0 1 2 3 4 5
2
3 4
1 1
4
1 1 1 1
4
4 4
1 1
2 2
3 3