#include <bits/stdc++.h>
const int mod = 1e9 + 7;
using namespace std;
int N = 1000000001;
vector<bool> sieve(N, 1);
void sieveMaker() {
  sieve[0] = 0;
  sieve[1] = 0;
  for (int i = 1; i * i <= N; i++) {
    if (sieve[i]) {
      for (int j = i * i; j <= N; j += i) {
        sieve[j] = 0;
      }
    }
  }
}
long long int mul(long long int x, long long int y) {
  return (x % mod * y % mod) % mod;
}
long long int add(long long int x, long long int y) {
  x += y;
  while (x >= mod) x -= mod;
  while (x < 0) x += mod;
  return x;
}
long long power(long long a, long long b) {
  a %= mod;
  long long res = 1;
  while (b > 0) {
    if (b & 1) res = mul(res, a);
    a = mul(a, a);
    b >>= 1;
  }
  return res % mod;
}
bool checkPalindrome(string s) {
  for (int i = 0; i < s.length(); i++) {
    if (s[i] != s[s.length() - i - 1]) {
      return false;
    }
  }
  return true;
}
void solve() {
  int n;
  cin >> n;
  vector<int> v(n);
  vector<int> a(n);
  for (int i = 0; i < n; i++) {
    cin >> v[i];
    a[i] = v[i];
  }
  if (n <= 2) {
    cout << "0\n";
    for (auto x : v) {
      cout << x << " ";
    }
    return;
  }
  sort(a.rbegin(), a.rend());
  for (int i = 1; i < n; i += 2) {
    v[i] = a[a.size() - 1];
    a.pop_back();
  }
  for (int i = 0; i < n; i += 2) {
    v[i] = a[a.size() - 1];
    a.pop_back();
  }
  int c = 0;
  for (int i = 0; i < n - 1; i++) {
    if (v[i] < v[i - 1] && v[i] < v[i + 1]) c++;
  }
  cout << c << "\n";
  for (auto x : v) {
    cout << x << " ";
  }
}
signed main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  ;
  long long int t;
  t = 1;
  while (t--) {
    solve();
  }
}
