#include <bits/stdc++.h>
using namespace std;
const int N = 1e7 + 5;
const int M = 25;
int A[M], B[M], n, m, x, y, cnt;
int dp[M * 4][M * 4];
void Min(int &x, int y) { x = min(x, y); }
int main() {
  cin >> n >> m;
  for (int i = 0; i < n; ++i) cin >> A[i];
  for (int i = 0; i < n; ++i) cin >> B[i];
  memset(dp, 0x3f, sizeof(dp));
  dp[0][0] = 0;
  for (int i = 0; i < n * 4; ++i) {
    for (int j = 0; j <= n + n; ++j)
      if (dp[i][j] <= 1e9) {
        Min(dp[i + 1][j + 1], dp[i][j] + A[i % n]);
        if (j) Min(dp[i + 1][j - 1], dp[i][j] + B[i % n]);
      }
  }
  if (m <= 3)
    cout << dp[n * m][0] << endl;
  else
    cout << dp[n * 4][0] + (m - 4) / 2 * (dp[n * 4][0] - dp[n * 2][0]) << endl;
}
