#include <bits/stdc++.h>

using namespace std;

#define FOR(i, a, b) for(int i = (a); i < (b); i++)
#define RFOR(i, a, b) for(int i = (a) - 1; i >= (b); i--)
#define SZ(a) int(a.size())
#define ALL(a) a.begin(), a.end()
#define PB push_back
#define MP make_pair
#define F first
#define S second 

typedef long long LL;
typedef vector<int> VI;
typedef pair<int, int> PII;
typedef double db;

bool hasBit(int mask, int i)
{
	return (mask >> i) & 1;
}

db area(int y, int h1, int h2)
{
	if (h1 > h2)
		swap(h1, h2);
	if (h1 >= y)
		return y;
	if (h2 <= y)
		return (h1 + h2) / 2.0;
	return y - (y - h1) * (y - h1) / (2.0 * (h2 - h1));
}

int main()
{
	ios::sync_with_stdio(0);
	cin.tie(0);
	int n, w, h;
	cin >> n >> w >> h;
	VI a(n + 2);
	FOR(i, 1, n + 1)
		cin >> a[i];
	int m = 2 * w - 1, fullMask = (1 << m) - 1;
	vector f(n + 1, VI(fullMask + 1));
	VI l(2 * w), r(2 * w);
	FOR(i, 1, n + 1)
	{
		FOR(mask, 0, fullMask + 1)
		{
			l.assign(2 * w, max(0, a[i] - h));
			r.assign(2 * w, a[i] + h);
			FOR(j, 0, m)
			{
				if (!hasBit(mask, j))
					continue;
				int k = i - j - 1;
				if (k < 1)
					continue;
				#warning
				FOR(p, 0, 2 * w)
				{
					int index = i + p - w;
					if (k - w <= index && index < k + w)
					{
						int& curL = l[index], curR = r[index];
						if (curL <= a[k] - h && a[k] - h <= curR)
						{
							curR = a[k] - h;
						}
						if (curL <= a[k] + h && a[k] + h <= curR)
						{
							curL = a[k] + h;
						}
					}
				}
			}
			FOR(p, 0, 2 * w)
			{
				int index = i + p - w;
				if (l[p] < r[p] && index >= 0 && index + 1 < n + 2)
				{
					f[i][mask] += area(r[p], a[index], a[index + 1]) - area(l[p], a[index], a[index + 1]);
				}
			}
		}
	}
	return 0;
}