/usr/share/doc/jflex/examples/cup/test.txt is in jflex 1.6.1-3.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5
2+4; 5*(6-3)+1; 6/3*5+20; 4*76/31; 1-1-1;