#include <bits/stdc++.h>
typedef long long ll;
using namespace std;

const int N=1e5+10;

int a[N];
ll dp[3*N];
int n;
ll m, k, sol;

inline bool check (ll x)
{
    ll ret=0, xt;
    for (int i=1;i<=n;i++)
    {
        dp[i]+=dp[i-1];
        if (1ll*a[i]+dp[i]>=x) continue;
        xt=x-1ll*a[i]-dp[i];
        dp[i]+=xt;
        dp[i+m]-=xt;
        ret+=xt;
    }
    memset(dp, 0, sizeof dp);
    return (ret<=k);
}

inline void solve ()
{
    scanf ("%d%lld%lld", &n, &m, &k);
    sol=1e10;
    for (int i=1;i<=n;i++)
    {
        scanf ("%d", &a[i]);
        sol=min(sol, 1ll*a[i]);
    }

    ll l=0, r=1e10, mid;
    while (l<=r)
    {
        mid=(l+r)/2;
        if (check(mid))
        {
            l=mid+1;
            sol=max(mid, sol);
        }
        else r=mid-1;
    }

    printf ("%lld\n", sol);
}

int main()
{
    int tp;
    cin >> tp;
    while (tp--) solve();

    return 0;
}