#include <bits/stdc++.h>
using namespace std;
const long long mod = 1000000007;
int main(int argc, const char* argv[]) {
  int n, m;
  cin >> n >> m;
  int a[n], b[n];
  for (int i = 0; i < n; ++i) cin >> a[i];
  for (int i = 0; i < n; ++i) cin >> b[i];
  int A[2 * n + 1][2 * n];
  int mn = 2000;
  for (int len = 0; len <= 2 * n; len += 2)
    for (int st = 0; st < 2 * n; ++st) {
      if (len == 0)
        A[len][st] = 0;
      else {
        A[len][st] = 1000;
        for (int dlt = 2; dlt <= len; dlt += 2)
          A[len][st] = min(A[len][st], A[dlt - 2][(st + 1) % (2 * n)] +
                                           A[len - dlt][(st + dlt) % (2 * n)] +
                                           a[st % n] + b[(st + dlt - 1) % n]);
      }
      if (len == 2 * n) mn = min(mn, A[len][st]);
    }
  int blk = m / 2;
  long long res = (long long)(A[2 * n][0]) + (long long)mn * (blk - 1);
  cout << res << endl;
}
