Getting on/off button from digital piano pedal

I have a digital piano pedal that is a standard 1/4 TS connector. I want to use the Arduino to get 1 / 0 data stream if it is pressed or not. I can handle the software part. I am perplexed by the circuit although I know it must be easy for some.

The female end is one of these babies:

Simple. I've attached leads from the tip end and the sleeve end. I have a suspicion that one must go through a resistor (10k?) to the ground. Another probably goes to the positive 5v of the arduino. But then one must go to the digital input... right? That's 3 and I only have 2 leads from the jack.

What am I missing?

Tip goes to the digital input pin. Sleeve goes to ground. When you press the pedal the digital input will read as zero. Oh, AND in the code you define the pin to be INPUT_PULLUP