We have a 3×3 square grid, where each square contains a lowercase English letters. The letter in the square at the i-th row from the top and j-th column from the left is c_{ij}.  Print the string of length 3 that can be obtained by concatenating the letters in the squares on the diagonal connecting the top-left and bottom-right corner of the grid, from the top-left to bottom-right.
for i in range(3):
  print(input()[i])
  
s=''
for i in range(3):
  temp=input()
  s=s+temp[i]
print(s)