Patuljci

Every day, while the dwarves are busy in the mines, Snow White prepares dinner for them; seven chairs, seven plates, seven forks and seven knives for seven hungry dwarves. One day nine dwarves came from the mines instead of seven (nobody knows how or why), each of them claiming to be one of Snow White's seven dwarves. Luckily, each dwarf wears a hat with a positive integer less than 100 written on it. Snow White, a famous mathematician, realised long ago that the sum of numbers on the hats of her seven dwarves was exactly 100. Write a program which determines which dwarves are legit, i.e. pick seven of nine numbers that add to 100.