import std;

void main () {
    int N, K, X;
    readln.read(N, K, X);
    auto A = readln.split.to!(int[]);

    auto rem = BinaryHeap!(int[], (a, b) => a < b)([]);
    auto take = BinaryHeap!(int[], (a, b) => b < a)([]);

    long ans = -long.max;
    long cur = 0;
    foreach (i; 0 .. N) {
        rem.insert(A[i]);

        if (i + 1 <= K) {
            take.insert(rem.front());
            cur += rem.front();
            rem.removeFront();
        }

        while (!rem.empty() && take.front() < rem.front()) {
            cur -= take.front();
            take.removeFront();
            take.insert(rem.front());
            cur += rem.front();
            rem.removeFront();
        }
        cur -= X;
        ans = max(ans, cur);
    }

    writeln(ans);
}

void read (T...) (string S, ref T args) {
    import std.conv : to;
    import std.array : split;
    auto buf = S.split;
    foreach (i, ref arg; args) {
        arg = buf[i].to!(typeof(arg));
    }
}