extracting numbers from a file, excluding fixed words

[dawenliu]

Hi, I have a file with this content:
xxxxxxx xxxxxxxxxx xxxxx xxxxxxx
1
0
0
0
1
1
0
(many more 1's and 0's to follow)
yyyyy yyyyyy yyy yyyyyy yyyyy yyy

The x's and y's are FIXED and known words which I will ignore, such as
"This is the start of the file" and "This is the end of the file".  The
digits 1 and 0 have UNKNOWN length.  I want to extract the digits and
store them in a file.  Any suggestions will be appreciated.