def parkan(s):
w = ""
for i in range(0, len(s), 3):
w = w + s[i]
for i in range(1, len(s), 3):
w = w + s[i]
return w
print(parkan("francuzmordo"))
ZGVmIHBhcmthbihzKToKCXcgPSAiIgoJZm9yIGkgaW4gcmFuZ2UoMCwgbGVuKHMpLCAzKToKCQl3ID0gdyArIHNbaV0KCWZvciBpIGluIHJhbmdlKDEsIGxlbihzKSwgMyk6CgkJdyA9IHcgKyBzW2ldCglyZXR1cm4gdwpwcmludChwYXJrYW4oImZyYW5jdXptb3JkbyIpKQ==