When a stage has you stuck, you don't have to stare at it forever. Open its hints panel for a nudge in the right direction.
Hints arrive gently. The first is there right away, and more become available the longer you sit with a stage. They're meant to point you toward the answer without spoiling the whole thing at once.
This stage is the demo: the answer isn't written here in the body. Open the hints and let one of them tell you what to type.
◆ Input solution