using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

public static class CollectionExtensions
{
    public static void AddRange<T>(this Collection<T> collection, IEnumerable<T> values)
    {
        foreach (var item in values)
        {
            collection.Add(item);
        }
    }

    public static T Find<T>(this Collection<T> collection, Predicate<T> predicate)
    {
        foreach (var item in collection)
        {
            if (predicate(item))
                return item;
        }
        return default(T);
    }

    public static Collection<T> FindAll<T>(this Collection<T> collection, Predicate<T> predicate)
    {
        Collection<T> all = new Collection<T>();
        foreach (var item in collection)
        {
            if (predicate(item))
                all.Add(item);
        }
        return all;
    }

    public static int FindIndex<T>(this Collection<T> collection, Predicate<T> predicate)
    {
        return FindIndex<T>(collection, 0, predicate);
    }

    public static int FindIndex<T>(this Collection<T> collection, int startIndex, Predicate<T> predicate)
    {
        return FindIndex(collection, startIndex, collection.Count, predicate);
    }

    public static int FindIndex<T>(this Collection<T> collection, int startIndex, int count, Predicate<T> predicate)
    {
        for (int i = startIndex; i < count; i++)
        {
            if (predicate(collection[i]))
                return i;
        }
        return -1;
    }

    public static T FindLast<T>(this Collection<T> collection, Predicate<T> predicate)
    {
        for (int i = collection.Count - 1; i >= 0; i--)
        {
            if (predicate(collection[i]))
                return collection[i];
        }
        return default(T);
    }

    public static int FindLastIndex<T>(this Collection<T> collection, Predicate<T> predicate)
    {
        return FindLastIndex<T>(collection, collection.Count - 1, predicate);
    }

    public static int FindLastIndex<T>(this Collection<T> collection, int startIndex, Predicate<T> predicate)
    {
        return FindLastIndex<T>(collection, startIndex, startIndex + 1, predicate);

    }

    public static int FindLastIndex<T>(this Collection<T> collection, int startIndex, int count, Predicate<T> predicate)
    {
        for (int i = startIndex; i >= startIndex - count; i--)
        {
            if (predicate(collection[i]))
                return i;
        }
        return -1;
    }

    public static void ForEach<T>(this Collection<T> collection, Action<T> action)
    {
        foreach (var item in collection)
        {
            action(item);
        }
    }

    public static int RemoveAll<T>(this Collection<T> collection, Predicate<T> match)
    {
        int count = 0;
        for (int i = 0; i < collection.Count; i++)
        {
            if (match(collection[i]))
            {
                collection.Remove(collection[i]);
                count++;
                i--;
            }
        }
        return count;
    }

    public static bool TrueForAll<T>(this Collection<T> collection, Predicate<T> match)
    {
        foreach (var item in collection)
        {
            if (!match(item))
                return false;
        }
        return true;
    }
}