C. Nested Segments
greedy; implementation; sortings
You are given a sequence a1, a2, ..., an of one-dimensional segments numbered 1 through n. Your task is to find two distinct indices i and j such that segment ai lies within segment aj.Segment [l1, r1] lies within segment [l2, r2] iff l1 ≥ l2 and r1 ≤ r2.Print indices i and j. If there are multiple answers, print any of them. If no answer exists, print -1 -1.
The first line contains one integer n (1 ≤ n ≤ 3·105) — the number of segments.Each of the next n lines contains two integers li and ri (1 ≤ li ≤ ri ≤ 109) — the i-th segment.
Print two distinct indices i and j such that segment ai lies within segment aj. If there are multiple answers, print any of them. If no answer exists, print -1 -1.
In the first example the following pairs are considered correct: (2, 1), (3, 1), (4, 1), (5, 1) — not even touching borders; (3, 2), (4, 2), (3, 5), (4, 5) — touch one border; (5, 2), (2, 5) — match exactly.