using System;
using static System.Console;
using System.Linq;
using System.Collections.Generic;
class Program
{
    static int[] NList => ReadLine().Split().Select(int.Parse).ToArray();
    static int[][] NArr(long n) => Enumerable.Repeat(0, (int)n).Select(_ => NList).ToArray();
    public static void Main()
    {
        Solve();
    }
    static void Solve()
    {
        var c = NList;
        var (n, k, l, p) = (c[0], c[1], c[2], c[3]);
        var map = NArr(n);
        WriteLine(Market(n, k, l, p, map));
    }
    static long Market(int n, int k, int l, int p, int[][] map)
    {
        var leftcnt = n / 2;
        var llist = BitList(map.Take(leftcnt).ToList());
        var rlist = BitList(map.Skip(leftcnt).ToList());
        llist.Sort((l, r) => l.val.CompareTo(r.val));
        rlist.Sort((l, r) => r.val.CompareTo(l.val));

        var cset = new HashSet<long>();
        foreach (var li in llist) if (l - li.cost >= 0) cset.Add(l - li.cost);
        foreach (var ri in rlist) cset.Add(ri.cost);
        var clist = new List<long>(cset);
        clist.Sort();
        var cdic = new Dictionary<long, int>();
        for (var i = 0; i < clist.Count; ++i) cdic[clist[i]] = i;

        var rightcnt = n - n / 2;
        var ftlist = new FenwickTree[rightcnt + 1];
        for (var i = 0; i < ftlist.Length; ++i) ftlist[i] = new FenwickTree(clist.Count);

        var ans = 0L;
        var cur = 0;
        foreach (var li in llist)
        {
            while (cur < rlist.Count && li.val + rlist[cur].val >= p)
            {
                ftlist[rlist[cur].cnt].Add(cdic[rlist[cur].cost], 1);
                ++cur;
            }
            if (l - li.cost < 0) continue;
            for (var i = 0; i < ftlist.Length && i + li.cnt <= k; ++i)
            {
                ans += ftlist[i].Sum(cdic[l - li.cost]);
            }
        }
        return ans;
    }
    static List<(int cnt, long cost, long val)> BitList(List<int[]> map)
    {
        var ans = new List<(int cnt, long cost, long val)>();
        var bitmax = 1 << map.Count;
        for (var b = 0; b < bitmax; ++b)
        {
            var tmp = b;
            var cnt = 0;
            var cost = 0L;
            var val = 0L;
            for (var i = 0; i < map.Count; ++i)
            {
                if (tmp % 2 == 1)
                {
                    ++cnt;
                    cost += map[i][0];
                    val += map[i][1];
                }
                tmp >>= 1;
            }
            ans.Add((cnt, cost, val));
        }
        return ans;
    }

    class FenwickTree
    {
        int size;
        long[] tree;
        public FenwickTree(int size)
        {
            this.size = size;
            tree = new long[size + 2];
        }
        public void Add(int index, int value)
        {
            ++index;
            for (var x = index; x <= size; x += (x & -x)) tree[x] += value;
        }
        /// <summary>先頭からindexまでの和(include index)</summary>
        public long Sum(int index)
        {
            ++index;
            var sum = 0L;
            for (var x = index; x > 0; x -= (x & -x)) sum += tree[x];
            return sum;
        }
    }
}