#include <bits/stdc++.h>
using namespace std;
template <class T>
inline void chkmin(T &a, T b) {
  if (a > b) a = b;
}
template <class T>
inline void chkmax(T &a, T b) {
  if (a < b) a = b;
}
int N, a[30], b[30], f[30][30], g[30][30];
void multi(int f[30][30], int g[30][30]) {
  int tmp[30][30], i, j, k;
  for (i = 0; i <= N; i++)
    for (j = 0; j <= N; j++) {
      tmp[i][j] = 2100000000;
      for (k = 0; k <= N; k++)
        if (f[i][k] < 2100000000 && g[k][j] < 2100000000)
          chkmin(tmp[i][j], f[i][k] + g[k][j]);
    }
  for (i = 0; i <= N; i++)
    for (j = 0; j <= N; j++) f[i][j] = tmp[i][j];
}
int main() {
  int M, i, j, dp, md, sum, u, v;
  scanf("%d%d", &N, &M);
  for (i = 0; i < N; i++) scanf("%d", &a[i]);
  for (i = 0; i < N; i++) scanf("%d", &b[i]);
  for (i = 0; i <= N; i++) {
    for (j = 0; j <= N; j++) f[i][j] = g[i][j] = 2100000000;
    f[i][i] = 0;
  }
  for (i = 0; i < (1 << N); i++) {
    dp = 0;
    md = 0;
    sum = 0;
    for (j = 0; j < N; j++) {
      if (i & (1 << j)) {
        sum += a[j];
        dp++;
      } else {
        sum += b[j];
        dp--;
      }
      chkmin(md, dp);
    }
    for (j = -md; j <= N; j++)
      if (j + dp >= 0 && j + dp <= N) {
        u = j;
        v = j + dp;
        chkmin(g[u][v], sum);
      }
  }
  for (i = 30; i >= 0; i--) {
    multi(f, f);
    if (M & (1 << i)) {
      multi(f, g);
    }
  }
  printf("%d\n", f[0][0]);
  return 0;
}
