s = "abcdefghijklmnop"
arr_of_two = []
for i in range(1, len(s), 2):
first = s[i - 1]
second = s[i]
arr_of_two.append((first, second))
for pair in arr_of_two:
print(pair)
'''
run:
('a', 'b')
('c', 'd')
('e', 'f')
('g', 'h')
('i', 'j')
('k', 'l')
('m', 'n')
('o', 'p')
'''