PD[X[8, 2, 9, 1], X[18, 4, 19, 3], X[14, 6, 15, 5], X[20, 8, 21, 7], X[26, 10, 1, 9], X[22, 12, 23, 11], X[6, 14, 7, 13], X[15, 24, 16, 25], X[4, 18, 5, 17], X[2, 20, 3, 19], X[12, 22, 13, 21], X[10, 24, 11, 23], X[25, 16, 26, 17]]