print $s;;
21

Dump $s;;
SV = PVNV(0x40b1eb8) at 0xa5b48
  REFCNT = 1
  FLAGS = (NOK,POK,pNOK,pPOK)
  IV = 20
  NV = 21
  PV = 0x40d3068 "21"\0
  CUR = 2
  LEN = 40