/usr/share/javascript/mathjax/jax/input/ is in libjs-mathjax 2.6.1-1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/javascript/mathjax/jax/input/AsciiMath/
/usr/share/javascript/mathjax/jax/input/AsciiMath/config.js
/usr/share/javascript/mathjax/jax/input/AsciiMath/jax.js
/usr/share/javascript/mathjax/jax/input/MathML/
/usr/share/javascript/mathjax/jax/input/MathML/config.js
/usr/share/javascript/mathjax/jax/input/MathML/entities/
/usr/share/javascript/mathjax/jax/input/MathML/entities/a.js
/usr/share/javascript/mathjax/jax/input/MathML/entities/b.js
/usr/share/javascript/mathjax/jax/input/MathML/entities/c.js
/usr/share/javascript/mathjax/jax/input/MathML/entities/d.js
/usr/share/javascript/mathjax/jax/input/MathML/entities/e.js
/usr/share/javascript/mathjax/jax/input/MathML/entities/f.js
/usr/share/javascript/mathjax/jax/input/MathML/entities/fr.js
/usr/share/javascript/mathjax/jax/input/MathML/entities/g.js
/usr/share/javascript/mathjax/jax/input/MathML/entities/h.js
/usr/share/javascript/mathjax/jax/input/MathML/entities/i.js
/usr/share/javascript/mathjax/jax/input/MathML/entities/j.js
/usr/share/javascript/mathjax/jax/input/MathML/entities/k.js
/usr/share/javascript/mathjax/jax/input/MathML/entities/l.js
/usr/share/javascript/mathjax/jax/input/MathML/entities/m.js
/usr/share/javascript/mathjax/jax/input/MathML/entities/n.js
/usr/share/javascript/mathjax/jax/input/MathML/entities/o.js
/usr/share/javascript/mathjax/jax/input/MathML/entities/opf.js
/usr/share/javascript/mathjax/jax/input/MathML/entities/p.js
/usr/share/javascript/mathjax/jax/input/MathML/entities/q.js
/usr/share/javascript/mathjax/jax/input/MathML/entities/r.js
/usr/share/javascript/mathjax/jax/input/MathML/entities/s.js
/usr/share/javascript/mathjax/jax/input/MathML/entities/scr.js
/usr/share/javascript/mathjax/jax/input/MathML/entities/t.js
/usr/share/javascript/mathjax/jax/input/MathML/entities/u.js
/usr/share/javascript/mathjax/jax/input/MathML/entities/v.js
/usr/share/javascript/mathjax/jax/input/MathML/entities/w.js
/usr/share/javascript/mathjax/jax/input/MathML/entities/x.js
/usr/share/javascript/mathjax/jax/input/MathML/entities/y.js
/usr/share/javascript/mathjax/jax/input/MathML/entities/z.js
/usr/share/javascript/mathjax/jax/input/MathML/jax.js
/usr/share/javascript/mathjax/jax/input/TeX/
/usr/share/javascript/mathjax/jax/input/TeX/config.js
/usr/share/javascript/mathjax/jax/input/TeX/jax.js