import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Scanner;
import java.util.TreeSet;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
			
		int N = sc.nextInt();
		int K = sc.nextInt();
		int X = sc.nextInt();
		
		long sum = 0;
		long sum1 = 0;
		
		int[] A = new int[N + 1];
		
		TreeSet<Integer> set = new TreeSet<>();
		
		List<Long> answerList = new ArrayList<>();
		
		for(int i = 1; i <= N; i++) {
			A[i] = sc.nextInt();
			set.add(A[i]);
			sum1 = sum1 + A[i];
			if(set.size() <= K) {
//				sum = sum + A[i] - X * i;
				
				sum = sum1 - X * i;
			}else {
				int first = set.pollFirst();
				sum1 = sum1 - first;
				sum = sum1 - X * i;
//				sum = sum + A[i] - first - X * i;
			}
//			System.out.println(set);
			answerList.add(sum);
//			System.out.println(sum);
		}
		
		Collections.sort(answerList);
		System.out.println(answerList.get(answerList.size() - 1));
	}
}