public class RecentCounter

    {

        Queue<int> Q;

        public RecentCounter()

        {

            Q = new Queue<int>();

            Q.Clear();

        }

        public int Ping(int t)

        {

            Q.Enqueue(t);

            while (Q.Peek() < t - )

            {

                Q.Dequeue();

            }

            return Q.Count;

        }

    }