골드 IIIYou are given the weights \(w_1, \dots, w_n\) of \(n\) molecules and a target range \([\ell, u]\). Find a non-empty subset of the molecules whose total weight lies in \([\ell, u]\), or report that no such subset exists.
It is guaranteed that \(\max_i w_i - \min_i w_i \le u - \ell\).
This is an interactive task. The grader sends you the arguments; you print the subset (or report impossibility). Because many subsets may be valid, the grader validates your subset rather than comparing it to a fixed answer.
Note. This is an adaptation of an IOI function-implementation task to an interactive stdin/stdout problem. The test data is RiseOJ-generated (self-validated against an independent brute force), not the official IOI data.
Interaction / I/O protocol
Input. The grader first sends one line with three integers \(n\), \(\ell\), \(u\). The second line contains \(n\) integers \(w_1 \dots w_n\).
Output. If a valid subset exists, print its size \(m\) (\(m \ge 1\)) on one line, then \(m\) distinct 1-based indices on the next line. If no valid subset exists, print a single line containing -1 (or 0).
Flush after printing. Any valid subset is accepted.
Example. For n=4, [l,u]=[10,12], weights 5 8 7 3:
(receive) 4 10 12
(receive) 5 8 7 3
(send) 2
(send) 1 3
The subset \(\{1,3\}\) has weight \(5+7=12 \in [10,12]\), so it is accepted.
- \(1 \le n \le 200\)
- \(1 \le w_i \le 1000\)
- \(1 \le \ell \le u \le 20000\)
- \(\max_i w_i - \min_i w_i \le u - \ell\)
The grader first sends one line with three integers \(n\), \(\ell\), \(u\). The second line contains \(n\) integers \(w_1 \dots w_n\).
If a valid subset exists, print its size \(m\) (\(m \ge 1\)) on one line, then \(m\) distinct 1-based indices on the next line. If no valid subset exists, print a single line containing -1 (or 0).
Flush after printing. Any valid subset is accepted.