def cells(D):
    n = len(D)/2 + 1
    a = list(reversed(D.reverse().to_area_sequence()))
    return [ (i,j) for j in range(1,n) for i in range(j) if j <= i+a[i]+1 ]

def peaks(D):
    ps = []
    for x in D.peaks():
        x += 1
        i = D[:x].count(0)
        j = x-i-1
        if i < j:
            ps.append( (i,j) )
    return ps

def statistic(D):
    cs = cells(D)
    ps = peaks(D)
    return sum( 1 for c in cs if sum( 1 for p in ps if p[0] <= c[0] < c[1] <= p[1] ) > 1 )