Answer
5
Work Step by Step
The pigeons are {1,3,5,7,9,11,13,15} and the pigeonholes are {(1,15), (3,13), (5,11), (7,9)}.
We need to find the least positive integer N such that $\left \lceil{\frac{N}{4}}\right \rceil $=2, so N=5.
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