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.
s1 = input()
s2 = input()
s3 = input()
print(''.join([s1[0], s1[1], s1[2]]))
s1 = input()
s2 = input()
s3 = input()
print(''.join([s1[0], s2[1], s3[2]]))