#include <stdio.h>
#include <malloc.h>
#include <string.h>

int main()
{
	long long int numberOfBuilding, floodHeight;
	numberOfBuilding = floodHeight = -1;
	scanf("%lld %lld", &numberOfBuilding, &floodHeight);

	long long int highestVolumeOfWater = 0, currentVolume = 0, isFilling = 0;

	for (int i = 0; i < numberOfBuilding; i++)
	{
		long long int currentBuildingHeight = -1;
		scanf("%lld", &currentBuildingHeight);

		if (currentBuildingHeight >= floodHeight)
			isFilling = 0;
		else if (currentBuildingHeight < floodHeight
			&& isFilling == 0)
			isFilling = 1;

		if (isFilling)
		{
			currentVolume += floodHeight - currentBuildingHeight;
//			printf("(building, volume) : %d %d\n", i + 1, currentVolume);
		}

		if (!isFilling || i == numberOfBuilding - 1)
		{
			if (currentVolume > highestVolumeOfWater)
			{
				highestVolumeOfWater = currentVolume;
				currentVolume = 0;
			}
		}
	}

//	printf("Biggest Volume : %d\n", highestVolumeOfWater);
	printf("%lld\n", highestVolumeOfWater);

	return 0;
}