AMO · 2027 · Grades 6-7 · Self-study SET 32 Question 10

A ladder has 7 rungs. An ant climbs from A, the middle of the bottom rung, to B, the middle of the top rung, without retracing any part of its path. How many different paths are possible? Count routes along the rungs and side rails only, ignoring pauses; no segment may be traversed twice.



**Input:** Enter the integer only, without units.