You have a RecentCounter class which counts the number of recent requests within a certain time frame.

Implement the RecentCounter class:

• RecentCounter(): Initializes the counter with zero recent requests
• ping(t): Adds a new request at time t, where t represents some time in milliseconds, and returns the number of requests that have happened in the past 3000 milliseconds (including the new request). Specifically, return the number of requests that have happened in the inclusive range [t - 3000, t]

It is guaranteed that every call to ping uses a strictly larger value of t than the previous call.

Examples

Example 1:

Input: ["RecentCounter", "ping", "ping", "ping", "ping"]
[[], [1], [100], [3001], [3002]]

Output: [null, 1, 2, 3, 3]

Explanation:
RecentCounter recentCounter = new RecentCounter();
recentCounter.ping(1);     // requests = [1], range is [-2999,1], return 1
recentCounter.ping(100);   // requests = [1, 100], range is [-2900,100], return 2
recentCounter.ping(3001);  // requests = [1, 100, 3001], range is [1,3001], return 3
recentCounter.ping(3002);  // requests = [1, 100, 3001, 3002], range is [2,3002], return 3

Constraints

• 1 <= t <= 10^9
• Each test case will call ping with strictly increasing values of t
• At most 10^4 calls will be made to ping

How the tests work: each test is a sequence of calls. operations[i] is the method called with arguments[i]; the first entry constructs the class. The expected output lists what every call returns — null for the constructor and for methods that return nothing.