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#include <iostream>
#include <algorithm>
#include <utility>


using namespace std;


static int n, k, iUsed, iBestDiffIndex, iBestDiffTop;

static int aHeights[1024];
static int aDiffs[1024];


static void ReadData()
{
	cin >> n >> k;

	for (int i = 0; i < n; ++i)
	{
		cin >> aHeights[i];
	}
}


static void InitDiffs()
{
	for (int i = 0; i < n - 1; ++i)
	{
		aDiffs[i] = abs(aHeights[i] - aHeights[i + 1]);
	}
}


static inline bool FindBestDiff()
{
	bool fFound = false;

	for (int i = 0; i < n - 1; ++i)
	{
		if (aDiffs[i] <= k)
			continue;

		if (!fFound)
		{
			fFound = true;
			iBestDiffIndex = i;
			iBestDiffTop = max(aHeights[i], aHeights[i + 1]);
			continue;
		}

		int iCandidateTop = max(aHeights[i], aHeights[i + 1]);

		if (iCandidateTop > iBestDiffTop)
		{
			iBestDiffTop = iCandidateTop;
			iBestDiffIndex = i;
		}
	}

	return fFound;
}


static inline void UpdateDiffLeft(int iPos)
{
	if (iPos > 0)
	{
		iPos--;
		aDiffs[iPos] = abs(aHeights[iPos] - aHeights[iPos + 1]);
	}
}


static inline void UpdateDiffRight(int iPos)
{
	if (iPos < n - 1)
	{
		aDiffs[iPos] = abs(aHeights[iPos] - aHeights[iPos + 1]);
	}
}


static void inline UpdateBestDiff()
{
	int iHigherPos = iBestDiffIndex;
	int iLowerPos = iBestDiffIndex + 1;

	if (aHeights[iLowerPos] > aHeights[iHigherPos])
	{
		swap(iHigherPos, iLowerPos);
	}

	int iDiff = aHeights[iHigherPos] - aHeights[iLowerPos];

	int iMissing = iDiff - k;

	iUsed += iMissing;

	aHeights[iLowerPos] += iMissing;

	UpdateDiffLeft(iLowerPos);
	UpdateDiffRight(iLowerPos);
}


int main()
{
	// freopen("sample_input.txt", "r", stdin);
	// freopen("sample_output.txt", "w", stdout);

	ReadData();
	InitDiffs();

	iUsed = 0;

	while (FindBestDiff())
	{
		UpdateBestDiff();
	}

	cout << iUsed;
}