x is a pair of lists of sorted numbers:
q)N:10*1000*1000;show x:{asc N?10*N}each``
1 3 15 35 40 44 50 55 56 68 107 115 137 141 148 152 15..
6 10 18 25 52 62 65 84 110 113 114 137 146 168 169 173 17..
what is better than a naive:
q)\t asc raze x
1710
?