FIRST: 1 2 3 4  against  5 6 7 8
 ├ LEVEL → the impostor hides among 9 10 11 12
 │    SECOND: 9 10 11  against  1 2 3
 │     ├ LEVEL      → it is 12. THIRD: 12 against 1 — down HEAVY, up LIGHT
 │     ├ LEFT DOWN  → 9, 10 or 11 HEAVY. THIRD: 9 against 10 — lower is it; level means 11
 │     └ RIGHT DOWN → 9, 10 or 11 LIGHT. THIRD: 9 against 10 — higher is it; level means 11
 ├ LEFT DOWN → 1-4 HEAVY or 5-8 LIGHT
 │    SECOND: 1 2 5  against  3 6 9
 │     ├ LEFT DOWN  → 1H, 2H or 6L. THIRD: 1 against 2 — lower is HEAVY; level: 6 LIGHT
 │     ├ RIGHT DOWN → 3H or 5L.     THIRD: 3 against 9 — down: 3 HEAVY; level: 5 LIGHT
 │     └ LEVEL      → 4H, 7L or 8L. THIRD: 7 against 8 — higher is LIGHT; level: 4 HEAVY
 └ RIGHT DOWN → the same dance, mirrored
      SECOND: 1 2 5  against  3 6 9
       ├ RIGHT DOWN → 1L, 2L or 6H. THIRD: 1 against 2 — higher is LIGHT; level: 6 HEAVY
       ├ LEFT DOWN  → 3L or 5H.     THIRD: 3 against 9 — up: 3 LIGHT; level: 5 HEAVY
       └ LEVEL      → 4L, 7H or 8H. THIRD: 7 against 8 — lower is HEAVY; level: 4 LIGHT
                                        — I.W-A., the Affair of the Forty Thimbles, 1938