A container is divided by a removable partition. On one side is 1.0 mol of helium gas, on the other side is 1.0 mol of neon gas, each at the same temperature and pressure. The partition is suddenly removed, and the gases mix without changing temperature or total volume. Indicate whether the entropy of the system after mixing is greater than, less than, or equal to the entropy before mixing, and provide a brief justification in one sentence.