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

#define int long long
#define rep(i, n) for(int i = 0; i < (int)(n); ++i)

int solve(void) {
    int N, K, X;
    cin >> N >> K >> X;
    vector<int> A(N);
    rep(i, N) cin >> A[i];
    
    priority_queue<int, vector<int>, greater<int>> que;
    int quesum = 0, ans = -1e18;
    rep(i, N) {
    	que.push(A[i]);
    	quesum += A[i];
    	
    	if(que.size() > K) {
    		quesum -= que.top();
    		que.pop();
    	}
    	
    	ans = max(ans, quesum - (i + 1) * X);
    }
    
    cout << ans << "\n";
    
    return 0;
}

signed main(void) {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);
    
    int Testcases = 1;
    //cin >> Testcases;
    while(Testcases--) solve();
    
    return 0;
}