#!/usr/bin/env python3

import sys

input_file = sys.argv[1]

with open(input_file) as fd:
    lines = [line.rstrip() for line in fd.readlines()]


def is_safe(report) -> bool:
    acc = sorted(report)
    dec = acc[::-1]
    if report != acc and report != dec:
        return False
    for i in range(len(report) - 1):
        diff = abs(report[i] - report[i + 1])
        if diff < 1 or diff > 3:
            return False
    else:
        return True


safe_num = 0
for line in lines:
    report = [int(level) for level in line.split(" ")]
    possible_reports = [report]
    for i in range(len(report)):
        rep = report.copy()
        rep.pop(i)
        possible_reports.append(rep)
    for rep in possible_reports:
        if is_safe(rep):
            safe_num += 1
            break

print(safe_num)