print(''.join([i for x,i in enumerate(input()) if x%3 !=0]))

 s=input()
for i in range(len(s)):
    if i%3==0:
        s=s.replace(s[i],' ',1)
print(s.replace(' ',''))

 s=input()
a=len(s)
for i in range(-a,0,3):
    s=s.replace(s[i],'',1)
print (s)

 >>> a = list("Python")
>>> del a[::3]
>>> "".join(a)
'yton'