Drink Slush

Chef is operating a slush machine. The machine produces slush drinks with $M$ flavors (numbered $1$ through $M$); for each valid $i$, the maximum number of drinks with flavour $i$ the machine can produce is $C_i$. Chef expects $N$ customers to come buy slush drinks today. The customers are numbered $1$ through $N$ in the order in which they buy the drinks. For each valid $i$, the favorite flavour