def test(arr):
    flagDown = int(arr[1])>int(arr[0])
    for i in range(1,len(arr)):
        diff = int(arr[i])-int(arr[i-1]) if flagDown else int(arr[i-1])-int(arr[i])
        if diff > 3 or diff < 1:
            return False
    return True

out = 0
with open('input02.txt') as file:
    for line in file:
        arr = line.split()
        flagSafe = True
        if not test(arr):
            for k in range(0,len(arr)):
                fixarr = arr.copy()
                del fixarr[k]
                if test(fixarr):
                    out += 1
                    break
        else:
            out += 1

print(out)