A trisubstituted compound ‘A’, C10H12O2 gives neutral FeCl3 test positive. Treatment of compound ‘A’ with NaOH and CH3Br gives C11H14O2 , with hydroiodic acid gives methyl iodide and with hot conc. NaOH gives a compound B, C10H12O2 . Compound ‘A’ also decolorises alkaline KMnO4 . The number of π bond/s present in the compound ‘A’ is _______