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

long long gcd(long long x, long long y) {
	if (x < y) swap(x, y);
	while (y > 0) {
		long long r = x % y;
		x = y;
		y = r;
	}
	return x;
}

long long lcm(long long x, long long y) {
	return x * y / gcd(x, y);
}

long long solve(vector<long long> A, long long M, long long L) {
	long long N = A.size();

	vector<long long> rui(2 * N);
	rui[0] = A[0];
	for (int i = 1; i < 2 * N; i++) {
		rui[i] = rui[i - 1] + A[(i * (L % N)) % N];
	}

	if (L <= N) {
		long long sum = 0;
		for (int i = 0; i < N; i++) {
			sum += A[i];
		}
		vector<long long> ans(L, (M / L) * sum);
		M %= L;
		for (int i = 0; i < N; i++) {
			if ((i * L) % N < L && N * M - 1 - (i * L) % N >= 0) {
				ans[(i * L) % N] += rui[i + (N * M - 1 - (i * L) % N) / L] - rui[i] + A[(i * L) % N];
			}
		}
		long long max_ = -1000000000000000000;
		for (int i = 0; i < L; i++) {
			max_ = max(max_, ans[i]);
		}
		return max_;
	}

	else {
		long long sum = 0;
		for (int i = 0; i < N; i++) {
			sum += A[i];
		}
		vector<long long> ans(N, (M / L) * sum);
		M %= L;
		for (int i = 0; i < N; i++) {
			if (N * M - 1 - (i * (L % N)) % N >= 0) {
				ans[(i * (L % N)) % N] += rui[i + (N * M - 1 - (i * (L % N)) % N) / L] - rui[i] + A[(i * (L % N)) % N];
			}
		}
		long long max_ = -1000000000000000000;
		for (int i = 0; i < N; i++) {
			max_ = max(max_, ans[i]);
		}
		return max_;
	}
}

int main() {
	long long N, M, L; cin >> N >> M >> L;
	vector<long long> A(N);
	for (int i = 0; i < N; i++) cin >> A[i];

	long long max_ = -1000000000000000000;
	for (int i = 0; i < gcd(N, L); i++) {
		vector<long long> B;
		for (int j = 0; j < N / gcd(N, L); j++) {
			B.push_back(A[j * gcd(N, L) + i]);
		}
		max_ = max(max_, solve(B, M, L / gcd(N, L)));
	}

	cout << max_ << endl;
}