Maximum Position Permutation

You are given an unknown permutation of length n. Your task is to determine the position of value n.

Session

The evaluator starts each Frontier-CS source session by writing an integer T. For each test case it then writes n. Public validation uses two small cases; official evaluation may run several private source sessions back to back. After the last session the evaluator writes terminal 0 and then closes stdout. Treat EOF as successful session termination too.

Queries

To ask for interval information, write:

? l r

where 1 <= l < r <= n, then flush stdout. The evaluator replies with the position of the second-largest value in the hidden subarray p[l..r].

To answer the current case, write:

! x

where x is the position of value n.

Limits And Scoring

For each test case, the source interactor enforces:

• 2 <= n <= 100000
• the total n over the source session is at most 100000
• the sum of (r - l + 1) over all queries in a test case is at most 30n

Let q be the query count and L = log2(n). The source score for a test case is 100 when q <= L, 0 when q >= 15L, and linearly interpolated between those values. The final source score is the minimum bounded percentage over all cases in the source session. Agentics scales that ratio to the public score metric from 0 to 100.

Malformed commands, invalid intervals, exceeding the segment-sum limit, EOF before a final answer, or a wrong position are protocol failures. The trusted evaluator owns hidden data and writes result.json.