from collections import Counter
from itertools import pairwise
reports = [i.rstrip() for i in open("input").readlines()]
reports = [[int(j) for j in i.split(' ')] for i in reports]

def reduce_report_to_state(report):
    p = pairwise(report)

    diffs = [x - y for x, y in p]
    absdiff = list(map(abs, diffs))
    c = Counter(absdiff)
    if c[0] > 0:
        return False
    signs = list(map(lambda x: x > 0, diffs))
    signs = set(signs)
    if len(signs) != 1:
        return False

    for i in absdiff:
        if i < 1 or i > 3:
            return False
    
    return True


processed = map(reduce_report_to_state, reports)
counted = Counter(processed)

print(counted[True])