=== step 0 === ..... ..... 121.. ..... ..... === step 1 === ..... .1... .2... .1... ..... === step 2 === ..... ..... 121.. ..... ..... === step 3 === ..... .1... .2... .1... ..... === step 4 === ..... ..... 121.. ..... ..... === step 5 === ..... .1... .2... .1... ..... === step 6 === ..... ..... 121.. ..... ..... === step 7 === ..... .1... .2... .1... ..... === step 8 === ..... ..... 121.. ..... ..... === step 9 === ..... .1... .2... .1... ..... === step 10 === ..... ..... 121.. ..... .....