#include<bits/stdc++.h>

using namespace std;

int n, m, k, a[1000005];
long long pre[1000005];

int main() {
    cin >> m >> n >> k;
    for (int i = 1; i <= m; i++)
        cin >> a[i];
    sort(a + 1, a + m + 1);
    
    for (int i = 1; i <= m; i++)
        pre[i] = pre[i - 1] + a[i];
    
    long long Ans = -2;

    for (int i = n; i <= m; i++) {
        /// goi ban thu i la cao nhat
        /// (i - 1, i - 2, i - 3, ... sao cho du n thang
        /// (i - n + 1)
        /// tap the cac ban [i - n + 1, i]
        if (a[i] - a[i - n + 1] <= k)
             Ans = max(Ans, pre[i] - pre[i - n]);
    }
    cout << Ans;

}