The seconds from (0,0) → (0, 1 )→ (1, 1 )→ (1, 0) are 1 s, 2 seconds, 3 seconds and (1) respectively.

When n=5, n? +n=5？ +5=30 seconds,

When the particle moves to the 30th second, it reaches (5,5).

The particle then moves to the left for 35-30=5 seconds.

At this time, the ordinate of the particle is 5-5=0,

∴ The coordinates of the particle position after No.35 are (5,0).