#include <iostream>
#include <string>
#include <utility>
#include <algorithm>
#include <map>
#include <set>
#include <vector>
#include <cmath>
#include <cstdlib>
#include <queue>
#include <stack>
#include <iomanip>
#include <fstream>
#include <unordered_map>
#include <unordered_set>
#include <assert.h>
using namespace std;


#define REP(i, n) for(ll i = 0;i < n;i++)
#define REPR(i, n) for(ll i = n;i >= 0;i--)
#define FOR(i, m, n) for(ll i = m;i < n;i++)
#define FORR(i, m, n) for(ll i = m;i >= n;i--)
#define REPO(i, n) for(ll i = 1;i <= n;i++)
#define ll long long
#define INF (ll)1 << 60
#define MINF (-1 * INF)
#define ALL(n) n.begin(),n.end()
#define MOD 1000000007
#define P pair<ll, ll>

ll ans = 0;
vector<ll> dp(11000, INF);
int main() {
	ll n, v;
	cin >> n >> v;
	vector<ll> s(n), r(n);
	
	REP(i, n) {
		cin >> s[i];
		ans += s[i];
	}
	v -= n;
	if (v <= 0) {
		cout << ans << endl;
		return 0;
	}
	r[0] = s[0];
	REP(i, n - 1) r[i + 1] = r[i] + s[i + 1];
	vector<pair<double, ll>> p(n);
	REP(i, n) p[i] = pair<double, ll>((double)r[i] / (i + 1), i);
	sort(ALL(p));
	if (v > 10000) {
		v -= 10000;
		ans += r[p[0].second] * (v / (p[0].second + 1));
		v %= p[0].second + 1;
		v += 10000;
	}
	dp[0] = 0;
	REP(i, n) {
		REP(j, v + 1) {
			dp[min(v, j + i + 1)] = min(dp[min(v, j + i + 1)], dp[j] + r[i]);
		}
	}
	cout << ans + dp[v] << endl;
}