wzip

#!/usr/bin/awk -f

NR == 1 {
	last=$1        
	printf("%s",$1)
	next
}
{
	for(i=0;i<=length(last);i++){                
		if(substr(last,0,i)!=substr($1,0,i)){
			break;
		}
	}                     
	back=length(last)-i+1;
	printf("%d%s",back,substr($1,i));   # decimal digits, for now...
	last=$1
}