#!/usr/bin/awk -f

NR == 1 {

	last=$1

	printf("%s",$1)

	next

}

{

	for(i=1;i<=length(last);i++){

		if(substr(last,1,i)!=substr($1,1,i)){

			break;

		}

	}

	back=length(last)-i+1;

	printf("%d%s",back,substr($1,i));   # decimal digits, for now...

	last=$1

}