=== step 0 === ..... ..1.. ..1.. ..1.. ..... === step 1 === ..... ..... .111. ..... ..... === step 2 === ..... ..1.. ..1.. ..1.. ..... === step 3 === ..... ..... .111. ..... ..... === step 4 === ..... ..1.. ..1.. ..1.. ..... === step 5 === ..... ..... .111. ..... ..... === step 6 === ..... ..1.. ..1.. ..1.. ..... === step 7 === ..... ..... .111. ..... ..... === step 8 === ..... ..1.. ..1.. ..1.. ..... === step 9 === ..... ..... .111. ..... ..... === step 10 === ..... ..1.. ..1.. ..1.. .....