from collections import Counter
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, outer_level=True):
    last = None
    diff = None
    sign = 0

    for index, item in enumerate(report):
        bad = False
        if not last:
            last = item
            continue

        diff = item - last
        if diff == 0:
            print("diff bad")
            bad = True

        thissign = 1 if diff > 0 else -1
        print(thissign, diff)
        if sign == 0:
            sign = thissign
        
        if sign != thissign:
            print("sign bad")
            bad = True
        
        adiff = abs(diff)
        print(adiff)

        if adiff > 3 or adiff < 1:
            print("range bad")
            bad = True

        last = item
        if bad:
            return False
    return True

def reduce_with_deference(report):
    verdict = reduce_report_to_state(report)
    if not verdict:
        for i in range(len(report) - 1):
            sliced = report[:i + 1] + report[i + 2:]
            print(report)
            print(sliced)
            second_result = reduce_report_to_state(
                    sliced
            )
            if second_result:
                return True
                continue

    return verdict

results = []
for i in reports:
    results.append(reduce_with_deference(i))

print(
    sum(
        [1 if i else 0 for i in results]
    )
)