s = 'fieurioewuyucnmz,cnmkbobbbobobobofiuweoruobobboobobobobooboboboboo'
count = 0
start = 0
while start <= len(s)-3:
    if 'bob' in s:
        start = s.find('bob')
        count += 1
        s = s[start + 1:len(s)]
        start = 0
    else:
        start = len(s) + 1
print("Number of bob occurs is: ") + str(count)