def error_count(levels: list[int]) -> bool:
    i = 0
    # figure out the diffs
    diffs = []
    while i < len(levels) - 1:
        curr, nxt = levels[i], levels[i+1]
        diffs.append(curr - nxt)
        i += 1
    neg = len(list(filter(lambda d: d < 0, diffs)))
    pos = len(list(filter(lambda d: d > 0, diffs)))
    big = len(list(filter(lambda d: abs(d) > 3, diffs)))
    zer = len(list(filter(lambda d: d == 0, diffs)))
    errors = big + zer
    errors += int((neg == 0 and pos == len(diffs))) + int((neg == len(diffs) and pos == 0))
    return errors



with open('data.input') as file:
    reports = [[int(i) for i in line.split()] for line in file]



# 0 or 1 is now tolerable
safe = 0
for report in reports:
    # print(error_count(report))
    safe += int(error_count(report) <= 1)
else:
    print('safe', safe)