# run with awk -f combine.awk < input | awk -f part2.awk 
length == 0 {
  #print "onesafe", onesafe
  S+= onesafe>0  # if at least one variant is safe, then report is safe
  onesafe = 0
  next
}
{
  p = ($2 -$1) < 0 ? -1 : 1  # uphill or downhill
  safe = 1
  for (i=2;i<=NF;i++) {
    d = ($i - $(i-1))
    q = d < 0 ? -1 : 1
    if (q != p || d>3 || d<-3 || d == 0) {
      safe = 0
      break
    } 
  }
  #print NR, $0 , p, safe
  onesafe += safe
}

END {
  print S
}