Guess the order of pins through trial-and error.
Pin 3: XOR of two hardcoded numbers
Pin 1: XOR or multiple hardcoded numbers
Pin 5: `rand()` after a `srand()` with a fixed number
Pin 2: `rand()` after a `srand()` with the `time()`, and it prints the time.
Pin 4: `rand()` (seeded from previous stage), a bunch of operations, and XOR+sum comparison to a fixed number.