def print_x_pattern(S):
   if not s.isalpha() or len (s)==0 or len(s) >50:
       print("Invalid input")
    return
   n = len(s)
   for i in range (n)
    line =[' ' for _in range(n)]
    line[i] =s[i]
    line[n -1 - i] = s[n -1 -i]
    print(''.join(line))