#include <bits/stdc++.h>
using namespace std;
using pii = pair<long long, long long>;
const long long inf = 1e18 + 7;
template <class T>
using vec = vector<T>;
vec<vec<long long>> mult(vec<vec<long long>> a, vec<vec<long long>> b) {
  long long n = a.size();
  vec<vec<long long>> ans(n, vec<long long>(n, inf));
  for (long long i = 0; i < n; ++i) {
    for (long long j = 0; j < n; ++j) {
      for (long long k = 0; k < n; ++k) {
        ans[i][j] = min(ans[i][j], a[i][k] + b[k][j]);
      }
    }
  }
  return ans;
}
vec<vec<long long>> pw(vec<vec<long long>> a, long long b) {
  if (!b) {
    vec<vec<long long>> q(a.size(), vec<long long>(a.size(), inf));
    for (long long i = 0; i < a.size(); ++i) {
      q[i][i] = 0;
    }
    return q;
  }
  if (b % 2 == 1) {
    return mult(a, pw(mult(a, a), b / 2));
  }
  return pw(mult(a, a), b / 2);
}
void run() {
  long long n;
  cin >> n;
  long long m;
  cin >> m;
  vector<long long> a(n);
  for (long long& i : a) cin >> i;
  vector<long long> b(n);
  for (long long& i : b) cin >> i;
  long long N = 2 * n + 1;
  vec<vec<long long>> ar(N, vec<long long>(N, inf));
  for (long long i = 0; i < N; ++i) {
    vec<vec<long long>> dp(n + 1, vec<long long>(2 * N, inf));
    dp[0][i] = 0;
    for (long long len = 1; len <= n; ++len) {
      for (long long bal = 0; bal < 2 * N; ++bal) {
        if (bal) {
          dp[len][bal] = min(dp[len][bal], dp[len - 1][bal - 1] + a[len - 1]);
        }
        if (bal != 2 * N - 1) {
          dp[len][bal] = min(dp[len][bal], dp[len - 1][bal + 1] + b[len - 1]);
        }
      }
    }
    for (long long j = 0; j < N; ++j) {
      ar[i][j] = min(ar[i][j], dp[n][j]);
    }
  }
  ar = pw(ar, m);
  cout << ar[0][0];
}
int32_t main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  long long tt = 1;
  while (tt--) {
    run();
    cout << '\n';
  }
}
