#include <bits/stdc++.h>
#define ll long long
#define pii pair <int, int>
#define fi first
#define se second
#define pb push_back

using namespace std;
mt19937 rnd(chrono::steady_clock::now().time_since_epoch().count());
const int N = 1e6+5, M = 1e6;
const ll inf = 0x3f3f3f3f3f3f3f3f;
int n, k, dq[N], ft, ed;
inline int read () {
	#define gc getchar
	int x = 0; char ch = gc();
	while (!isdigit(ch)) ch = gc();
	while (isdigit(ch)) x = x*10+(ch^48), ch = gc();
	return x;
	#undef gc
}
struct vec {
	ll a[N];
	inline void clr () { memset(a, -0x3f, sizeof a); }
	inline void init () { clr(); a[1] = 0; }
	friend vec operator * (const vec & a, const vec & b) {
		vec c; c.clr();
		for (int i = 1;i <= M;i++) {
			if (a.a[i] >= 0)
				for (int j = 1;j*i <= M;j++) c.a[i*j] = max(c.a[i*j], a.a[i]+b.a[j]);
		}
		return c;
	}
}a;

vec qpow (vec x, int y) {
	vec res; res.init();
	while (y) {
		if (y&1) res = res*x;
		x = x*x; y >>= 1;
	}
	return res;
}
bool chk (vec &x, int i, int j, int z) {
	return (__int128)(x.a[i]-x.a[j])*(j-z) >= (__int128)(x.a[j]-x.a[z])*(i-j);
}

signed main () {
	n = read(); k = read();
	a.clr();
	for (int i = 1;i <= n;i++) a.a[i] = read();
	ll ad = 0; ad += max(0, k-30)*a.a[1]; k = min(k, 30);
	vec x = qpow(a, k/2), y;
	if (k&1) y = x*a; else y = x;
	ft = 1; ed = 0;
	for (int i = 1;i <= M;i++) {
		while (ed-ft >= 1 && chk(x, i, dq[ed], dq[ed-1])) --ed;
		dq[++ed] = i;
	}
	ll mx = -inf;
	for (int i = M;i >= 1;i--) {
		while (ed-ft >= 1 && (x.a[dq[ft+1]]-x.a[dq[ft]]) >= 1ll*(dq[ft+1]-dq[ft])*i) ft++;
		mx = max(mx, x.a[dq[ft]]+y.a[i]-1ll*i*dq[ft]);
	}
	cout << mx+ad;
	return 0;
}