3
1 51 52 
ABABAAAAABABBBBAAAABBBBAABBBBBAABABABAABAAAAAAAAAB??????????????????????????????????????????????????
ABABAAAAABABBBBAAAABBBBAABBBBBAABABABAABAAAAAAAAABABABAAAAABABBBBAAAABBBBAABBBBBAABABABAABAAAAAAAAAB
ABABAAAAABABBBBAAAABBBBAABBBBBAABABABAABAAAAAAAAABAABABAAAAABABBBBAAAABBBBAABBBBBAABABABAABAAAAAAAAAB
-1