def parkan(s):
w = ""
for i in range(0, len(s), 2):
w = w + s[i]
for i in range(1, len(s), 2):
w = w + s[i]
return w
print(parkan("fronty"))
print(parkan("tajne"))
ZGVmIHBhcmthbihzKToKCXcgPSAiIgoJZm9yIGkgaW4gcmFuZ2UoMCwgbGVuKHMpLCAyKToKCQl3ID0gdyArIHNbaV0KCWZvciBpIGluIHJhbmdlKDEsIGxlbihzKSwgMik6CgkJdyA9IHcgKyBzW2ldCglyZXR1cm4gdwpwcmludChwYXJrYW4oImZyb250eSIpKQpwcmludChwYXJrYW4oInRham5lIikp