#!/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
}