#include <bits/stdc++.h>
using namespace std;
const int mod = 1e9 + 7;
const int inf = 0x3f3f3f3f;
int a[100], b[100];
int dp[100][100];
int main() {
  int n, m;
  cin >> n >> m;
  for (int i = 1; i <= n; i++) {
    cin >> a[i];
    a[i + 2 * n] = a[i + n] = a[i];
  }
  for (int i = 1; i <= n; i++) {
    cin >> b[i];
    b[i + 2 * n] = b[i + n] = b[i];
  }
  int ans, mn = mod;
  for (int k = 1; k <= n; k++) {
    dp[0][0] = 0;
    dp[1][1] = a[k];
    for (int i = 2; i <= 2 * n; i++) {
      if (i % 2 == 0) dp[i][i / 2] = dp[i - 1][i / 2] + b[i + k - 1];
      for (int j = i / 2 + 1; j <= i; j++) {
        if (i != j)
          dp[i][j] =
              min(dp[i - 1][j] + b[i + k - 1], dp[i - 1][j - 1] + a[i + k - 1]);
        else
          dp[i][j] = dp[i - 1][j - 1] + a[i + k - 1];
      }
    }
    if (k == 1)
      mn = ans = dp[2 * n][n];
    else
      mn = min(mn, dp[2 * n][n]);
  }
  cout << ans + mn * (m / 2 - 1) << endl;
  return 0;
}
