If you roll a number not in is_bad_side, you receive that many dollars (e. g., if you roll the number 2 and 2 is not a bad side -- meaning the second element of the vector is_bad_side is 0 , then you receive 2 dollars). Repeat step 2. If you roll a number in is_bad_side, then you lose all the money obtained in previous rolls and the game ends.