#!/usr/bin/perl -w

       while(<DATA>) {
          chomp;
          if ( /^-{0,}P{1,1}T{0,}\d{1,}[Y|M|D|H|S]{1,1}/ ) {
              print "$_ matches\n";
          } else {
              print "$_ NO match\n";
          }
       }
       __DATA__
       PnYnMnDTnHnMnS
       -P1Y
       P3Y3M3DT3H3M3S
       P3M3Y3DT3H3M3S
       P334Y3DT3H3M3S
       PT2H
       5T
       PT
       P5M6DT
       P5M6DT9
       P600T6S