from operator import itemgetter

def punt_central(intervals):
    pmin = min(intervals, key=itemgetter(0))[0]
    # equival a pmin = min(intervals, key=lambda iv: iv[0])[0]
    pmax = max(intervals, key=itemgetter(1))[1]
    # equival a pmax = max(intervals, key=lambda iv: iv[1])[1]
    p = (pmin + pmax)/2
    return p