#include<bits/stdc++.h>
using namespace std;
int main()
{
    int t,n;
    int c,d,s;
    cin>>t;
    while(t--)
    {
        cin>>n;
        int arr[n];
        for(int i=0;i<n;i++)
        scanf("%d",&arr[i]);
        cin>>c>>d>>s;
        int max = arr[0];
        long long ans= (c-1)*arr[0];
        for(int i=1;i<n;i++)
        {
            if(arr[i]>max)
            {
                ans+=((arr[i]-max)*(c-1));
                max = arr[i];
             }
        }
        cout<<ans<<endl;
    }
}

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

MgozCjIgMiAyCjMgNSA1CjIKMyAyCjIgMSAx

2
3
2 2 2
3 5 5
2
3 2
2 1 1