#include <bits/stdc++.h>
using namespace std;
void solve(int *arr, int n, int *p, int g, int d) {
  int i;
  for (i = 0; i < n / 2; i++) {
    if (i % 2 == 0) {
      arr[i] = p[n / 2 - 1 - i];
      arr[n - 1 - i] = p[n / 2 + i];
    } else {
      arr[i] = p[n / 2 + i];
      arr[n - 1 - i] = p[n / 2 - i - 1];
    }
  }
  if (d % 2 == 0) {
    for (i = 0; i < n; i++) {
      cout << arr[i] << " ";
    }
  } else {
    int *a = new int[d];
    a[d / 2] = g;
    for (i = 0; i < d / 2; i++) {
      a[i] = arr[i];
    }
    for (i = d / 2 + 1; i < d; i++) {
      a[i] = arr[i - 1];
    }
    for (i = 0; i < d; i++) {
      cout << a[i] << " ";
    }
  }
}
int main() {
  int n, i;
  cin >> n;
  if (n == 1 || n == 2) {
    cout << 1 << endl;
    cout << 1 << endl;
    return 0;
  }
  if (n == 3) {
    cout << 2 << endl;
    cout << 1 << " " << 3 << endl;
    return 0;
  }
  int *p = new int[n];
  for (i = 0; i < n; i++) {
    p[i] = i + 1;
  }
  if (n % 2 == 0) {
    cout << n << endl;
    int *arr = new int[n];
    solve(arr, n, p, p[n / 2], n);
  } else {
    cout << n << endl;
    int *arr = new int[n - 1];
    int *q = new int[n - 1];
    int k = 0;
    for (i = 0; i < n; i++) {
      if (i != n / 2) {
        q[k] = p[i];
        k++;
      }
    }
    int g = p[n / 2];
    solve(arr, n - 1, q, g, n);
  }
  return 0;
}
