#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define ull unsigned ll
#define nl "\n"
#define sz(x) int(x.size())
#define NumOfDigit(w) log10(w) + 1
#define fill(arr, val)  memset(arr, val , sizeof(arr))
#define PI 3.141592654
#define ceil(w, m) (((w) / (m)) + ((w) % (m) ? 1 : 0))
#define all(v) v.begin(), v.end()
#define rall(v) v.rbegin(), v.rend()
#define fi first
#define se second
#define cin(v) for (auto&i:v) cin >> i;
#define cout(v) for (auto&i:v) cout << i << " ";
#define fixed(n) fixed << setprecision(n)
//#define MOD  1e9 + 7


void IO(){
    ios_base::sync_with_stdio(false); cin.tie(nullptr); cout.tie(nullptr);
}
void files(){
    //freopen("filename.in" , "r" ,stdin);
            #ifndef ONLINE_JUDGE
              freopen("input.txt", "r", stdin);  freopen("output.txt", "w", stdout);
            #endif
}



void solve(){



ll n , k , d , w;

cin >> n >> k >> d >> w;

vector < ll > v(n);

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

ll ans = 0  , start =0 , tempK = k;

for(int i =0 ; i < n ;i++){

  // start point
   if(k == tempK){
       ans++ ;
       start= v[i];
       k--;
       continue;
   }

       if(k > 0 and  (abs(v[i] - start) <= d ) or ( abs(v[i]- w - start) <= d )){
           k-- ;

           if( k ==0)
               k= tempK;
       }

       else // start new dose
           k = tempK-1 , start = v[i] ,  ans++;
}


cout << ans << nl;

}


int main(){
                 IO();       //  files();

    int testCase=1;  // one test case
     cin >> testCase ;
 while(testCase--)
        solve();  // my code

    return 0;
}