#include <bits/stdc++.h>
using namespace std;
long long int exp(long long int x, long long int y) {
  long long int res = 1;
  x = x % 1000000007;
  while (y > 0) {
    if (y & 1) res = (res * x) % 1000000007;
    y = y >> 1;
    x = (x * x) % 1000000007;
  }
  return res;
}
long long int modinv(long long int x) { return exp(x, 1000000007 - 2); }
long long int add(long long int a, long long int b) {
  a %= 1000000007, b %= 1000000007;
  a = ((a + b) % 1000000007 + 1000000007) % 1000000007;
  return a;
}
long long int sub(long long int a, long long int b) {
  a %= 1000000007, b %= 1000000007;
  a = ((a - b) % 1000000007 + 1000000007) % 1000000007;
  return a;
}
long long int mul(long long int a, long long int b) {
  a %= 1000000007, b %= 1000000007;
  a = ((a * b) % 1000000007 + 1000000007) % 1000000007;
  return a;
}
long long int gcd(long long int a, long long int b) {
  if (b == 0) return a;
  return gcd(b, a % b);
}
long long int Log2n(long long int n) { return (n > 1) ? 1 + Log2n(n / 2) : 0; }
long long int fac[100009];
long long int ncr_mod(long long int n, long long int k) {
  long long int ans = fac[n];
  ans *= modinv(fac[k]);
  ans %= 1000000007;
  ans *= modinv(fac[n - k]);
  ans %= 1000000007;
  return ans;
}
vector<long long int> v_prime;
void Sieve(long long int n) {
  bool prime[n + 1];
  memset(prime, true, sizeof(prime));
  for (long long int p = 2; p * p <= n; p++) {
    if (prime[p] == true) {
      for (long long int i = p * p; i <= n; i += p) prime[i] = false;
    }
  }
  for (long long int p = 2; p <= n; p++)
    if (prime[p]) v_prime.emplace_back(p);
}
vector<long long int> v_factor;
void factors(long long int n) {
  for (long long int i = 1; i <= sqrt(n); i++) {
    if (n % i == 0) {
      if (n / i == i)
        v_factor.emplace_back(i);
      else {
        v_factor.emplace_back(i), v_factor.emplace_back(n / i);
      };
    }
  }
  sort(v_factor.begin(), v_factor.end());
}
void out(vector<long long int>& a) {
  for (long long int i = 0; i < a.size(); i++) cout << a[i] << " ";
  cout << endl;
}
signed main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  cerr.tie(0);
  ;
  long long int t = 1;
  while (t--) {
    long long int n, i, x, y, ok = 0, sum = 0, ans = 0, j, k, cnt = 0, m, c = 0;
    long long int h[100009] = {0};
    cin >> n;
    multiset<long long int> s;
    vector<long long int> a(n, 0), v(n, 0);
    for (i = 0; i < n; i++) {
      cin >> a[i];
      s.insert(a[i]);
    }
    if (n == 1 || n == 2) {
      cout << 0 << endl;
      out(a);
      continue;
    }
    long long int pp = n - 1;
    while (1) {
      if (s.size() == 0) {
        break;
      }
      auto it = s.end();
      it--;
      v[pp] = *it;
      s.erase(s.find(*it));
      pp -= 2;
      if (pp < 0) break;
    }
    cnt = 0;
    long long int l = n - 1;
    long long int r = n - 3;
    while (1) {
      if (l < 0 || r < 0) break;
      long long int res = min(v[l], v[r]);
      auto it1 = s.lower_bound(res);
      if (it1 != s.begin()) {
        it1--;
        v[l - 1] = *it1;
        s.erase(it1);
      } else {
        v[l - 1] = *it1;
        s.erase(it1);
      }
      l -= 2;
      r -= 2;
      if (l < 0 || r < 0) break;
    }
    if (s.size() != 0) {
      v[0] = *(s.begin());
    }
    cnt = 0;
    for (i = 1; i < v.size() - 1; i++) {
      if (v[i] < v[i - 1] && v[i] < v[i + 1]) cnt++;
    }
    cout << cnt << endl;
    out(v);
  }
}
