Codeforces 319C Kalila and Dimna - Why It Works

Slopes $b_i$ are strictly decreasing. When we add lines in order $i = 1, 2, \ldots$, each new line has a smaller slope than all previous. Lines are added to the deque in decreasing slope order. For queries: we need $a_j$ values. The problem states $a_1 < a_2 < \ldots < a_n$ (increasing).

So queries are sorted too. Both conditions met: sorted slopes (decreasing) and sorted queries (increasing). The simple $O(n)$ deque CHT applies directly.