Twelve problems from Codeforces and AtCoder, the two biggest competitive programming judges. They are submitted on those sites and come in the order of this week's lessons: sets first, then maps, then multisets.
The statements are in English (and Japanese, on AtCoder). AtCoder checks the
exact words of the answer, so print Yes and No just as the statement does.
Read the limits before choosing a type: some keys go up to 10⁹.