Modular Array

Vilas is currently doing the Travas $N$ day challenge, where on the $i^{th}$ day he is supposed to run $x$ metres, where $x$ is an integer and $0 \leq x \leq (i - 1)$, that is he can run anywhere from $0$ metres to $i - 1$ metres on the $i^{th}$ day. Since Vilas is superhuman (and also immortal) he manages to complete the challenge. However he realises that he had forgotten to record on certain da