#! /usr/bin/gawk -f
# Last edited on 2020-11-17 23:58:40 by jstolfi

BEGIN { N1 = 10; N2 = 3; } 
($1 == dtini) { print; next; }
($1 == dtfin) { print; next; }
($1 < "2018-10-21") {
  if ((FNR % N1) == 0) { print; }
  next;
}
($1 <= "2019-04-29") { print; next; }
// { 
  if ((FNR % N2) == 0) { print; }
  next;
}