What does it mean that an electron quantum numbers are n1= 4 - l1?

I'm trying to solve some exercises from the 2017 IChO, and the problem 6-A1 states that

in first ionization, an electron with the quantum numbers $n_1 = 4 - l_1$ is removed.

Now, I've never seen this way of expressing quantum numbers, and I don't know what it's supposed to mean, so I would appreciate it if someone could dumb it down to me.