#include <bits/stdc++.h>
#pragma GCC optimize "trapv"
using namespace std;
const long long int MOD = 1e9 + 7;
void print() { cout << "\n"; }
template <typename T, typename... Args>
void print(T a, Args... arg) {
  cout << a << " ";
  print(arg...);
}
void input() { return; }
template <typename T, typename... Args>
void input(T &a, Args &...arg) {
  cin >> a;
  input(arg...);
}
long long int gcdExtended(long long int a, long long int b, long long int *x,
                          long long int *y) {
  if (a == 0) {
    *x = 0, *y = 1;
    return b;
  }
  long long int x1, y1;
  long long int gcd = gcdExtended(b % a, a, &x1, &y1);
  *x = y1 - (b / a) * x1;
  *y = x1;
  return gcd;
}
long long int power(long long int a, long long int b) {
  long long int res = 1;
  while (b) {
    if (b & 1LL) res = res * a;
    b >>= 1LL;
    a = a * a;
  }
  return res;
}
long long int modPower(long long int a, long long int b) {
  long long int res = 1;
  while (b) {
    if (b & 1L) res = (res % MOD * a % MOD) % MOD;
    b >>= 1;
    a = (a % MOD * a % MOD) % MOD;
  }
  return res;
}
long long int modInverse(long long int b, long long int m) {
  long long int x, y;
  long long int g = gcdExtended(b, m, &x, &y);
  if (g != 1) return -1;
  return (x % m + m) % m;
}
long long int modDivide(long long int a, long long int b,
                        long long int m = MOD) {
  a = a % m;
  long long int inv = modInverse(b, m);
  if (inv == -1)
    return -1;
  else
    return (inv * a) % m;
}
void run_case() {
  long long int n;
  cin >> n;
  long long int a[n];
  for (long long int i = 0; i < n; i++) {
    cin >> a[i];
  };
  sort(a, a + n);
  vector<long long int> v;
  for (long long int i = 0; i < n / 2; i++) {
    v.push_back(a[n - i - 1]);
    v.push_back(a[i]);
  }
  if (n % 2) v.push_back(a[n / 2]);
  long long int ans = 0;
  if (n % 2)
    ans = n / 2;
  else
    ans = (n - 1) / 2;
  print(ans);
  for (long long int i = 0; i < n; i++) {
    cout << v[i] << " ";
  }
  cout << "\n";
  ;
}
signed main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  run_case();
  return 0;
}
