Intervals (3)

Write a program that, given two intervals, tells if one is inside the other, and computes the interval corresponding to their intersection, or tells that it is empty.

Input

Input consists of four integer numbers $a_1$ , $b_1$ , $a_2$ , $b_2$ that represent the intervals $[a_1,b_1]$ and $[a_2,b_2]$ . Assume $a_1\le b_1$ and $a_2\le b_2$ .

Output

Print ‘=’ if the intervals are equal, ‘1’ if the first is inside the second (but they are not equal), ‘2’ if the second is inside the first (but they are not equal), or ‘?’ otherwise. Also, print “[]” if the intersection is empty, or “[ $x$ , $y$ ]” if this is their non-empty intersection.

Problem information

Author: Unknown
Translator: Carlos Molina

Generation: 2026-01-25T12:19:07.913Z