class Solution(object):

def repeatedStringMatch(self, a, b):

"""

:type a: str

:type b: str

:rtype: int

"""

# check for invalid inputs

if (len(a) < 1) | (len(b) < 1) | (len(a) > 1e4) | (len(b) > 1e4):

return -1

# minimum repetitions of a for b to be a substring

minRep = int(len(b)/len(a))

rep = minRep

# increment the number of repetitions at most twice (as in the worst case below)

# b b b b b b b b

# a a a-a a a-a a a-a a a

while (rep <= min( minRep + 2, 1e4 )) and not (b in a*(rep)):

rep += 1

# The cycle exits when b is a substring of a repeated or if all the possible concatenations have been already checked

# In the second case, the output is set to -1

if not (b in a*(rep)):

rep = -1

return rep