1 class Solution
 2 {
 3 public:
 4     int numberOfRounds(string startTime, string finishTime)
 5     {
 6         int x = stoi(startTime.substr(0, 2)) * 60 + stoi(startTime.substr(3, 2));
 7         int y = stoi(finishTime.substr(0, 2)) * 60 + stoi(finishTime.substr(3, 2));
 8         if (y < x) y += 24 * 60;
 9         y = y / 15 * 15;
10         return max(0, (y - x)) / 15;
11     }
12 };