#include <bits/stdc++.h>

using i64 = long long;
using u64 = unsigned long long;
using u32 = unsigned;

using u128 = unsigned __int128;
using i128 = __int128;

int main() {
    std::ios::sync_with_stdio(false);
    std::cin.tie(nullptr);

    int N, K;
    i64 X;
    std::cin >> N >> K >> X;

    i64 sum = 0, ans = -2e18;
    std::multiset<i64> s;
    
    for (int i = 0; i < N; i++) {
        i64 cur;
        std::cin >> cur;
        if (K) {
            sum += cur;
            s.insert(cur);
            K--;
        } else {
            i64 mi = *s.begin();
            if (cur > mi) {
                sum = sum - mi + cur;
                s.erase(s.begin());
                s.insert(cur);
            }
        }
        ans = std::max(ans, sum - 1LL * (i + 1) * X);
    }
    std::cout << ans << '\n';

    return 0;
}