4. Masha has 2 kg of "Swallow" candies, 3 kg of "Truffle" candies, 4 kg of "Bird's Milk" candies, and 5 kg of "Citron" candies. What is the maximum number of New Year's gifts she can make if each gift must contain 3 different types of candies, 100 grams of each?
Answer: 45

Solution: Even if Masha puts "Citron" in all the gifts, she will still have 2+3+4 = 9 kg of candies left, and in each gift, she must put at least 200g (and if she doesn't put Citron in all of them, then more than 200g). This means there can be no more than 45 gifts. 45 gifts can be made if she creates 5 gifts of the type Swallow+Truffle+Citron, 15 gifts of the type Swallow+Bird's Milk + Citron, and 

25 gifts of the type Truffle+Bird's Milk + Citron.

Comment for graders: Here, half a point can be given for the correct selection without proving that it is optimal.