#include <bits/stdc++.h>
using namespace std;
long long n, m;
long long a[100];
long long ans = 1e18;
long long po[100];
map<long long, long long> ma;
long long fun(long long left1) {
  long long ans1 = 1e18;
  if (left1 <= 0) {
    return 0;
  }
  for (long long i = 0; i < n; i++) {
    long long left = left1;
    long long temp = 0;
    if (po[i] >= left)
      left = 0, temp = a[i];
    else if (left % po[i] == 0) {
      temp = left / po[i];
      temp *= a[i];
      left = 0;
    } else {
      temp = left / po[i];
      temp *= a[i];
      left = left % po[i];
    }
    if (ma[left] != 0)
      ans1 = min(ans1, temp + ma[left]);
    else {
      ma[left] = fun(left);
      ans1 = min(ans1, temp + ma[left]);
    }
  }
  return ans1;
}
int main() {
  cin >> n >> m;
  for (long long i = 0; i < n; i++) cin >> a[i];
  po[0] = 1;
  for (long long i = 1; i <= 30; i++) {
    po[i] = po[i - 1] * 2;
  }
  for (long long i = 0; i < n; i++) {
    long long left = m;
    long long temp;
    if (po[i] >= left)
      left = 0, temp = a[i];
    else if (left % po[i] == 0) {
      temp = left / po[i];
      temp *= a[i];
      left = 0;
    } else {
      temp = left / po[i];
      temp *= a[i];
      left = left % po[i];
    }
    ans = min(ans, temp + fun(left));
  }
  cout << ans;
  return 0;
}
