import java.util.*;
import java.util.zip.*;
import java.util.List;
import java.util.regex.*;
import java.util.concurrent.*;
import java.util.concurrent.atomic.*;
import java.util.concurrent.locks.*;
import java.util.function.*;
import javax.swing.*;
import javax.swing.event.*;
import javax.swing.text.*;
import javax.swing.table.*;
import java.io.*;
import java.net.*;
import java.lang.reflect.*;
import java.lang.ref.*;
import java.lang.management.*;
import java.security.*;
import java.security.spec.*;
import java.awt.*;
import java.awt.event.*;
import java.awt.image.*;
import java.awt.geom.*;
import javax.imageio.*;
import java.math.*;
import java.time.Duration;
import java.lang.invoke.VarHandle;
import java.lang.invoke.MethodHandles;
class main {

static class SynchronizedCircularBuffer<A> {
  SynchronizedCircularBuffer() {}
  A[] buffer;
  long base; // elements dropped due to overcapacity
  int size;  // elements actually contained
  
  SynchronizedCircularBuffer(int capacity) {
    buffer = (A[]) new Object[capacity];
  }
  
  synchronized void add(A a) {
    if (size == buffer.length) {
      --size;
      ++base;
    }
    buffer[(int) ((base+size) % buffer.length)] = a;
    ++size;
  }
  
  synchronized A get(long pos) {
    if (pos < base || pos >= base+size) return null;
    return buffer[(int) (pos % buffer.length)];
  }
  
  synchronized int size() {
    return size;
  }
  
  synchronized int capacity() {
    return buffer.length;
  }
  
  synchronized boolean isFull() {
    return size() == capacity();
  }
  
  synchronized long getBase() {
    return base;
  }
}}