//compiler options: /t:library
using System;

public class ListInt {
  public int info;
  public ListInt next;
  
  public ListInt(int n, ListInt nxt) {
    info = n;
    next = nxt;
  }

  public static int Length(ListInt p) {
    int br = 0;
    while(p != null) {
      br++;
      p = p.next;
    }
    return br;
  }

  public static bool Equal(ListInt p, ListInt q) {
    while(p != null && q != null) {
      if(p.info != q.info) { break; }
      p = p.next;
      q = q.next;
    }
    return p == null && q == null;
  }

  public static ListInt Copy(ListInt p) {
    if(p == null) { return null; }
    ListInt first = new ListInt(p.info, null);
    ListInt last = first;
    p = p.next;
    while(p != null) {
      last.next = new ListInt(p.info, null);
      last = last.next;
      p = p.next;
    }
    return first;
  }
  
  public static ListInt Rev(ListInt p) {
    if(p == null || p.next == null) { return p; }
    ListInt q = p.next;
    p.next = null;
    ListInt r;
    do {
      r = p;
      p = q;
      q = q.next;
      p.next = r;
    } while(q != null);
    return p;
  }
}