class HitCounter:

    def __init__(self):
        self.counters = dict()
        

    def hit(self, timestamp: int) -> None:
        self.counters[timestamp] = self.counters.get(timestamp, 0) + 1
        
        
    def getHits(self, timestamp: int) -> int:
        return sum([v for k,v in self.counters.items() if k <= timestamp and timestamp - k < 300])