P2925 [USACO08DEC] Hay For Sale S

Farmer John suffered a terrible loss when giant Australian cockroaches ate the entirety of his hay inventory, leaving him with nothing to feed the cows. He hitched up his wagon with capacity $C$ ($1\le C\le 50000$) cubic units and sauntered over to Farmer Don's to get some hay before the cows miss a meal. Farmer Don had a wide variety of $H$ ($1\le H\le 5000$) hay bales for sale, each with its own volume ($1\le V_i\le C$). Bales of hay, you know, are somewhat flexible and can be jammed into the oddest of spaces in a wagon. FJ carefully evaluates the volumes so that he can figure out the largest amount of hay he can purchase for his cows. Given the volume constraint and a list of bales to buy, what is the greatest volume of hay FJ can purchase? He can't purchase partial bales, of course. Each input line (after the first) lists a single bale FJ can buy.

\* Line $1$: Two space-separated integers: $C$ and $H$; \* Lines $2\dots H+1$: Each line describes the volume of a single bale: $V_i$.

\* Line $1$: A single integer which is the greatest volume of hay FJ can purchase given the list of bales for sale and constraints.

The wagon holds $7$ volumetric units; three bales are offered for sale with volumes of $2$, $6$, and $5$ units, respectively. Buying the two smaller bales fills the wagon.