For example:

text
5 5
1 2
2 4
3 4
1 3
3 5
2 5
Optimal route:
Start with the 'down' gear.
2→1: go downhill (0 shifts, gear stays 'down').
1→3: go uphill → 1 shift (gear becomes 'up'), score = 1.
3→5: go uphill (0 shifts). Total: 1 shift.

My algorithm outputs 2 because it doesn't account for the current gear when storing distances.

Nevertheless, I got Accepted.