""" day2 part 1 """

import fileinput

count = 0

def is_safe(report):
    prev = report[0]
    direction = None
    safe = True
    for item in report[1:]:
        delta = item - prev
        print(direction,delta)

        if delta == 0 or delta > 3 or delta < -3:
            print(f'unsafe (delta={delta})')
            safe = False
            break

        if (direction is not None) and ((delta > 0) != (direction > 0)):
            print(f'unsafe (delta={delta} dir={direction})')
            safe = False
            break

        direction = delta
        prev = item

    return safe

def remove_one(report):
    for i in range(len(report)):
        yield report[:i] + report[i+1:]

for line in fileinput.input():
    report = [int(x) for x in line.split()]

    if is_safe(report):
        count += 1

print(count)