#include <bits/stdc++.h>
using namespace std;
const int INF = 2000000000;
const int MOD = 1000000007;
int A[11 * 2], B[2 * 11], N, M, TN;
long long DP[850][850], RES[11 * 2];
long long REC(int pos, int toGo) {
  if (toGo < 0) return INF;
  if (pos == TN) {
    if (toGo > 0) return INF;
    return 0;
  }
  long long &ret = DP[pos][toGo];
  if (~ret) return ret;
  ret = min(A[pos % N] + REC(pos + 1, toGo + 1),
            B[pos % N] + REC(pos + 1, toGo - 1));
  return ret;
}
int main(int argc, const char **argv) {
  ios::sync_with_stdio(false);
  long long tot = 0;
  while (cin >> N >> M) {
    M >>= 1;
    for (int i = 0; i <= (N - 1); ++i) cin >> A[i];
    for (int i = 0; i <= (N - 1); ++i) cin >> B[i];
    for (int i = 1; i <= 21; ++i) {
      memset(DP, -1, sizeof(DP));
      TN = (2 * i) * N;
      RES[i] = REC(0, 0);
    }
    if (M <= 21)
      tot = RES[M];
    else {
      long long diff = (RES[21] - RES[20]);
      tot = RES[20] + diff * (M - 20);
    }
    cout << tot << endl;
  }
  return 0;
}
