#include <bits/stdc++.h>
#define show(x) std::cerr << #x << " = " << x << std::endl
using ll = long long;
template <typename T>
constexpr T INF = std::numeric_limits<T>::max() / 4;
int main()
{
    std::cin.tie(0);
    std::ios::sync_with_stdio(false);
    int N;
    ll V;
    std::cin >> N >> V;
    std::vector<ll> C(N);
    ll sum = 0;
    for (auto& e : C) { std::cin >> e, sum += e, V--; }
    if (V <= 0) { return std::cout << sum << std::endl, 0; }
    for (int i = 1; i < N; i++) { C[i] += C[i - 1]; }
    std::vector<ll> dp(N * N, INF<ll>);  // 合計iリットル使う最安値
    dp[0] = 0;
    for (int i = 0; i < N; i++) {
        for (int j = i + 1; j < N * N; j++) { dp[j] = std::min(dp[j], dp[j - i - 1] + C[i]); }
    }
    if (V < N * N) { return std::cout << sum + dp[V] << std::endl, 0; }
    ll min = INF<ll>;
    for (int i = 0; i < N; i++) {
        const ll num = (V - N * N + i) / (i + 1);
        min = std::min(min, dp[V - num * (i + 1)] + num * C[i]);
    }
    std::cout << min + sum << std::endl;
    return 0;
}