import os

dir = os.path.dirname(os.path.abspath(__file__))

input_file = open(os.path.join(dir, './input.txt'), 'r')
lines = input_file.readlines()

new_list = []
num_lines = len(lines)
count = 0
for i in range(num_lines):
    int_value = int(lines[i])
    if i + 2 >= num_lines:
        break

    new_list.append(int(lines[i])+int(lines[i+1])+int(lines[i+2]))
    if i >= 1 and new_list[i] > new_list[i-1]:
        count = count+1

print(count)