#!/bin/sh

sed  -n '
/[a-zA-Z][a-zA-Z]*/q
h
:branch
n
/[0-9]0-9]*/{
	x;p
	b branch
	}
/[a-zA-Z][a-zA-Z]*/{
	H;g;s/\n//g;p
	s/.*//;x;d
	}
'