goal = [[0,1,2],[3,4,5],[6,7,8],[0,3,6],[1,4,7],[2,5,8],[0,4,8],[2,4,6]]
readlines.each{|line|
  arr = line.chomp.split("")
  flag = "d"
  goal.each{|i,j,k|
    if arr[i] != "s" && arr[i] == arr[j] && arr[j] == arr[k]
      flag = arr[i]
      break
    end
  }
  puts flag
}