#include <iostream>
#include <cstdio>
#include <string>
#include <sstream> 
#include <vector>
#include <set>
#include <map>
#include <queue>
#include <stack>
#include <cmath>
#include <algorithm>
#include <cstring>
#include <ctime>
#include <cassert>
using namespace std;
#define pb push_back
#define mp make_pair
#define pii pair<int,int>
#define vi vector<int>
#define vpii vector<pii>
#define SZ(x) ((int)(x.size()))
#define fi first
#define se second
#define FOR(i,n) for(int (i)=0;(i)<(n);++(i))
#define FORI(i,n) for(int (i)=1;(i)<=(n);++(i))
#define IN(x,y) ((y).find((x))!=(y).end())
#define ALL(t) t.begin(),t.end()
#define FOREACH(i,t) for (typeof(t.begin()) i=t.begin(); i!=t.end(); i++)
#define REP(i,a,b) for(int (i)=(a);(i)<=(b);++i)
#define REPD(i,a,b) for(int (i)=(a); (i)>=(b);--i)
#define REMAX(a,b) (a)=max((a),(b));
#define REMIN(a,b) (a)=min((a),(b));
#define DBG cerr << "debug here" << endl;
#define DBGV(vari) cerr << #vari<< " = "<< (vari) <<endl;

typedef long long ll;
const int INF = 1e9;

ll solve(const vector<int>& s, ll l, ll m) {
    ll cost = 0;
    for (int i = 0; i < s.size(); ++i) {
        cost += abs(m + i*l-s[i]);
    }
    return cost;
}

int main()
{
    ios_base::sync_with_stdio(0);
    int t;
    cin >> t;
    while (t--) {
        int n;
        ll l, a, b;
        cin >> n >> l >> a >> b;
        vector<int> s(n);
        for (int i = 0; i < n; ++i) {
            cin >> s[i];
        }
        sort(s.begin(), s.end());
        int lo = a;
        int hi = b - n*l;
        ll res = 1e18;
        while (hi-lo > 10) {
            int m1 = lo+(hi-lo)/3;
            int m2 = hi-(hi-lo)/3;
            ll f1 = solve(s, l, m1);
            ll f2 = solve(s, l, m2);
            if (f1 < f2) {
                hi = m2-1;
                REMIN(res, f1);
            } else {
                lo = m1+1;
                REMIN(res, f2);
            }
        }
        for (int m = lo; m <= hi; ++m) {
            ll f = solve(s, l, m);
            REMIN(res, f);
        }
        cout << res << endl;
    }
    return 0;
}