This problem is due to S. S. Patil in 1971. Suppose a cigarette requires three ingredients, tobacco, paper and match. There are three chain smokers. Each of them has only one ingredient with infinite supply. There is an agent who has infinite supply of all three ingredients. To make a cigarette, the smoker has tobacco (resp., paper and match) must have the other two ingredients paper and match (resp., tobacco and match, and tobacco and paper). The agent and smokers share a table. The agent randomly generates two ingredients and notifies the smoker who needs these two ingredients. Once the ingredients are taken from the table, the agent supplies another two. On the other hand, each smoker waits for the agent's notification. Once it is notified, the smoker picks up the ingredients, makes a cigarette, smokes for a while, and goes back to the table waiting for his next ingredients.

Please write a simple c++ program that simulates this system, with three smokers and the agent.