5. A supermarket is holding a promotional event, offering two packages in the discount area. Package $\mathrm{A}$ includes 2 bottles of milk, and Package $\mathrm{B}$ includes 3 bottles of cola. Each package comes with a free souvenir. After purchasing both types of packages, Xiao Long found that he bought a total of 50 bottles of milk and cola, and received 22 souvenirs. How many bottles of milk did Xiao Long buy?