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72.
set (protect) 6 first. oprions: 65????, 61????,????56, ????16, 561???, 165???, ?561??, ?165??, ??561?, ??165?, ???561, ???165.
1. 65????. options: 651432, 651234,652134,652314,652143,652341, 653214,653412,654123,654321,654132,654312, ->12.
2. 61???? ->12.
3. ????56 ->12
4. ????16 ->12
5. 651???. options: 651234,651432 ->2
6. 165???. ->2.
7. ?561??. options: 256134, 256143, 456123, 465132 ->4
8. ?165?? ->4
9. ??561? ->4
10. ??165? -> 4
11. ???561 ->2
12. ???165 ->2