Find all integers n≥3 such that among any n positive real numbers a_1, a_2, \hdots, a_n with \text{max}(a_1,a_2,\hdots,a_n) \leq n \cdot \text{min}(a_1,a_2,\hdots,a_n), there exist three that are the side lengths of an acute triangle. USA(J)MOUSAMO2012 USAJMO2012 USAMOgeometryFibonacciinequalities