The counters may be arranged in this order:--

R1, B2, Y3, O4, GS.

Y4, O5, G1, R2, B3.

G2, R3, B4, Y5, O1.

B5, Y1, O2, G3, R4.

O3, G4, R5, B1, Y2.

Amusements in Mathematics · 第 831 / 970 题