#include <bits/stdc++.h>
#define fi first
#define se second
#define rep(i,s,n) for (int i = (s); i < (n); ++i)
#define rrep(i,n,g) for (int i = (n)-1; i >= (g); --i)
#define all(a) a.begin(),a.end()
#define rall(a) a.rbegin(),a.rend()
#define len(x) (int)(x).size()
#define dup(x,y) (((x)+(y)-1)/(y))
#define pb push_back
#define eb emplace_back
#define Field(T) vector<vector<T>>
using namespace std;
using ll = long long;
using ull = unsigned long long;
template<typename T> using pq = priority_queue<T,vector<T>,greater<T>>;
using P = pair<int,int>;
template<class T>bool chmax(T&a,T b){if(a<b){a=b;return 1;}return 0;}
template<class T>bool chmin(T&a,T b){if(b<a){a=b;return 1;}return 0;}

int main() {
  int t;
  cin >> t;
  while(t--) {
    int n, l, k;
    cin >> n >> l >> k;
    vector<int> x(n);
    rep(i,0,n) cin >> x[i];
    sort(all(x));
    int m = 0;
    rep(i,0,n) {
      m = max(m, x[(i+k)%n] + (i+k >= n ? l : 0) - x[i]);
    }
    cout << (m+1)/2 << endl;
  }
  return 0;
}