perl -ne"print $1,'-',$2||1,' 'while /([A-Z][a-z]*)(\d+)?/g;print qq[\n]" CON
CH4N2O
C-1 H-4 N-2 O-1
C9H12N2O6
C-9 H-12 N-2 O-6
C5H11NO2
C-5 H-11 N-1 O-2
C5H4N4O2
C-5 H-4 N-4 O-2
C10H11N4O9P
C-10 H-11 N-4 O-9 P-1
C10H12N4O6
C-10 H-12 N-4 O-6
C5H10O5
C-5 H-10 O-5
C5H12O5
C-5 H-12 O-5
C5H10O5
C-5 H-10 O-5
C27H44O
C-27 H-44 O-1
C1694H2993O101
C-1694 H-2993 O-101
^Z