a = vector(199); nxt = vector(2); { print ("0 0"); r=1; d=1; k=0; for (n=1, 10 000, print (n " " v = nxt[1+r%2]+=d); if (n<=#a, a[n]=v; ); k++; if (k==abs(a[r]), k=0; r++; d=-d; if (r>#a, break; ); ); ); } quit