static void Main()
{
var h = ReadL();
int n = (int)h[0], k = (int)h[1];
long l = h[2], r = h[3];
var a = ReadL();
var n1 = n / 2;
var n2 = n - n1;
var gs1 = BruteForceHelper.CreateAllSumsForCount(a.Take(n1).ToArray());
var gs2 = BruteForceHelper.CreateAllSumsForCount(a.Skip(n1).ToArray());
var c = 0L;
for (int i1 = 0; i1 <= n1; i1++)
{
var i2 = k - i1;
if (i2 < 0 || n2 < i2)
{
continue;
}
var g1 = gs1[i1];
var g2 = gs2[i2];
Array.Sort(g1);
Array.Reverse(g1);
Array.Sort(g2);
var ls = new int[g1.Length];
var rs = new int[g1.Length];
foreach (var ij in TwoPointers(g1.Length, g2.Length + 1, (i, j) => j == g2.Length || g1[i] + g2[j] >= l))
{
ls[ij.i] = ij.j;
}
foreach (var ij in TwoPointers(g1.Length, g2.Length + 1, (i, j) => j == g2.Length || g1[i] + g2[j] > r))
{
rs[ij.i] = ij.j;
}
for (int i = 0; i < g1.Length; i++)
{
c += rs[i] - ls[i];
}
}
Console.WriteLine(c);
}
static void Main()
{
var h = ReadL();
int n = (int)h[0], k = (int)h[1];
long l = h[2], r = h[3];
var a = ReadL();
var n1 = n / 2;
var n2 = n - n1;
var gs1 = BruteForceHelper.CreateAllSumsForCount(a.Take(n1).ToArray());
var gs2 = BruteForceHelper.CreateAllSumsForCount(a.Skip(n1).ToArray());
var c = 0L;
for (int i1 = 0; i1 <= n1; i1++)
{
var i2 = k - i1;
if (i2 < 0 || n2 < i2)
{
continue;
}
var s1 = gs1[i1];
var s2 = gs2[i2];
Array.Sort(s2);
foreach (var x1 in s1)
{
var li = First(0, s2.Length, si => x1 + s2[si] >= l);
var ri = First(0, s2.Length, si => x1 + s2[si] > r);
c += ri - li;
}
}
Console.WriteLine(c);
}