output_description: Print the string obtained by concatenating all the characters in the odd-
  numbered positions.
  
  * * *
input_description: The input is given from Standard Input in the following format:
  
      
      
      s
attempt: from collections import defaultdict, Counter
  from itertools import product, groupby, count, permutations, combinations
  from math import pi, sqrt
  from collections import deque
  from bisect import bisect, bisect_left, bisect_right
  from string import ascii_lowercase
  from functools import lru_cache
  import sys
  
  sys.setrecursionlimit(10000)
  INF = float("inf")
  YES, Yes, yes, NO, No, no = "YES", "Yes", "yes", "NO", "No", "no"
  dy4, dx4 = [0, 1, 0, -1], [1, 0, -1, 0]
  dy8, dx8 = [0, -1, 0, 1, 1, -1, -1, 1], [1, 0, -1, 0, 1, 1, -1, -1]
  
  
  def inside(y, x, H, W):
      return 0 <= y < H and 0 <= x < W
  
  
  def ceil(a, b):
      return (a + b - 1) // b
  
  
  def main():
      s = input()
      print("".join(s[i] for i in range(0, len(s), 2)))
  
  
  if __name__ == "__main__":
      main()
  
problem_description: Statement
  
  You are given a string s consisting of lowercase English letters. Extract all
  the characters in the odd-indexed positions and print the string obtained by
  concatenating them. Here, the leftmost character is assigned the index 1.
samples: [{"input": "atcoder", "output": "acdr\n    \n\nExtract the first character `a`, the third character `c`, the fifth character\n`d` and the seventh character `r` to obtain `acdr`.\n\n* * *"}, {"input": "aaaa", "output": "aa\n    \n\n* * *"}, {"input": "z", "output": "z\n    \n\n* * *"}, {"input": "fukuokayamaguchi", "output": "fkoaaauh"}]