Don't open as unformatted, it will read your file as if it were binary data. Open as formatted instead, and use "*" format. Also, don't read in one line, as you would not read your data in the expected order.
program bob
implicit none
integer cnunit, n, maxn, box, i
parameter(maxn=108, cnunit=10)
real rx(maxn), ry(maxn)
open(unit=cnunit, file='bob.txt', status='old', form='formatted')
read(cnunit, *) n, box
print *, 'n=', n, 'box=', box
if(n .gt. maxn) stop 'n too large'
do i=1, n
read(cnunit, *) rx(i), ry(i)
print *, rx(i), ry(i)
end do
close(unit=cnunit)
end
Alternately, if you can't change the code, then change your input file to fit the needs of your program. The input file you give simply won't work: you need binary data, in the format expected by your compiler (there is the usual, non portable "record size"), and data must be given column-wise, not row-wise.