#include <bits/stdc++.h>
using namespace std;
int n, m, jj = 0;
long long a[22], b[22];
long long dp[44][44];
long long memo(int idx, int cnt) {
  long long res = (long long)(1e18);
  if (idx == 2 * n - 1) {
    if (cnt == 1) res = b[((idx + jj) % n)];
    return dp[idx][cnt] = res;
  }
  if (dp[idx][cnt] != -1) return dp[idx][cnt];
  if (cnt > 0) res = b[((idx + jj) % n)] + memo(idx + 1, cnt - 1);
  res = min(res, a[((idx + jj) % n)] + memo(idx + 1, cnt + 1));
  return dp[idx][cnt] = res;
}
int main() {
  memset(dp, -1, sizeof dp);
  cin >> n >> m;
  for (int i = 0; i < n; i++) cin >> a[i];
  for (int i = 0; i < n; i++) cin >> b[i];
  long long mn = memo(0, 0);
  long long ans = mn;
  for (jj = 1; jj < n; jj++) {
    memset(dp, -1, sizeof dp);
    mn = min(memo(0, 0), mn);
  }
  cout << (m / 2 - 1) * mn + ans << endl;
  return 0;
}
