AWK: Help inserting records between various matches

Hello, my apologizes if the title is a bit confusing. I am currently working with a series of files that have the form:

2
3
7
17
21

However, I need to insert records such that I have:

0 0
1 0
2 1
3 1
4 0
5 0
6 0
7 1
.... And so on.
Currently I have the following script:

awk '{{temp=$1;getline;temp2=$1};if((temp2-temp)>1){for(i=temp;i<temp2;i++){print i,0}}{print $1, 1}}' 

Which produces:

3 1
7 0
8 0
9 0
10 0
11 0
12 0
13 0
14 0
15 0
16 0
17 1
21 1

I've played around with this for awhile, but seem to have hit a brick wall ( :wall: ). Any help would be great.

Thanks

Try...

awk 'c<$1{while(c<$1-1)print ++c,0}{print c=$1,1}' c=-1 file1

That did it! Thanks I knew it had to be simpler than I what I was doing.