1Here is a comparison matrix which shows a case in which 2it is possible for the forward and backward scan in `diag' 3to meet along a nonzero length of diagonal simultaneous 4(so that bdiag[d] and fdiag[d] are not equal) 5even though there is no snake on that diagonal at the meeting point. 6 7 8 85 1 1 1 159 1 1 17 9 1 2 3 4 1060 11 1 2 121 13 2 2 3 4 1471 15 3 3 4 5 1685 17 4 3 4 5 1817 19 5 4 5 201 21 6 4 5 6 22183 23 7 5 6 7 2410 25 8 6 7 261 27 9 6 7 8 2812 29 7 8 9 10 3013 31 10 8 9 10 3214 33 10 9 10 3417 35 10 10 361 37 10 9 10 381 39 8 10 10 10 40183 41 8 7 9 9 9 4210 43 7 6 8 9 8 8 441 45 6 5 7 7 461 47 5 6 6 481 49 5 5 5 5050 51 5 4 4 4 521 53 4 3 3 5485 55 5 4 3 2 2 561 57 2 1 5817 59 5 4 3 2 1 1 601 61 1 0 62 85 1 1 1 159 1 1 17 63 64 65 66 67 68 69 70 71 72