学步园

//DP[i][j]表示第i月用j个工人的最小花费
//枚举+DP,k为上月使用的工人数
//if(j <= k)
//    cost = (hiring*(j-k)) + s*j + DP[i-1][k];
//else
//    cost = (firing*(k-j)) + s*j + DP[i-1][k];
//枚举j和k，将cost的最小值填入DP[i][j];
//结果为DP[month][....]的最小值
#include <iostream>
#include <cstring>
using namespace std;

int month;
int hiring,firing,salary;
int worker[13];
int DP[13][1000];

int main()
{
	while(cin>>month,month != 0)
	{
		cin>>hiring>>salary>>firing;
		int maxj = 0;
		
		for(int i = 1; i <= month; i++)
		{
			cin>>worker[i];
			if(maxj < worker[i])
			{
				maxj = worker[i];
			}
		}
		
		
		for(int i = worker[1]; i <= maxj; i++)
		{
			DP[1][i] = (hiring*i + salary*i);
		}

		int cost = 0;

		for(int i = 2; i <= month; i++)
		{
			for(int j = worker[i]; j <= maxj; j++)
			{
				int mins = 999999999;
				for(int k = worker[i-1]; k <= maxj; k++)
				{
					if(j >= k)
					{
						cost = (hiring*(j-k)) + salary*j + DP[i-1][k];
					}
					else
					{
						cost = (firing*(k-j)) + salary*j + DP[i-1][k];
					}
						
					if(cost < mins )
					{
						mins = cost;
					}
				}
				DP[i][j] = mins;
			}
		}
		int min = 999999999;
		for(int i = worker[month]; i <= maxj; i++)
		{
			if(min > DP[month][i])
			{
				min = DP[month][i];
			}
		}	
		cout<<min<<endl;

	}
	return 0;
}