13 Hello, World! 15 Hello, [ World! 15 Hello, ] World! 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 \ [] 1 1st 2nd 0 81 1024 4 5 1 q q\ \ \ 10