lines = [[int(n) for n in l.split()] for l in open("input.txt", 'r').read().splitlines()]

unsafe, unsafe2 = 0, 0

for report in lines:
    if report[0] == report[1]:
        unsafe += 1
        continue

    trend = -1 if report[0] > report[1] else 1

    for i in range(len(report) -1):
        if (trend == -1 and report[i] < report[i+1]) \
            or (trend == 1 and report[i] > report[i+1]) \
            or (report[i] == report[i+1]) \
            or (abs(report[i] - report[i+1]) > 3):
            
            unsafe += 1
            break

print(len(lines)-unsafe)