#include <bits/stdc++.h>
using namespace std;
long long int n, m, i, j, k, l, arr[200009], brr[200009], crr[200009], a, b, c,
    d, e, f, g, h;
vector<pair<long long int, pair<long long int, long long int> > > v;
int main() {
  scanf("%lld %lld", &n, &m);
  k = 0;
  for (i = 0; i < n; i++) scanf("%lld", &arr[i]);
  sort(arr, arr + n);
  for (i = 1; i < n; i++) {
    l = arr[i] - arr[i - 1];
    v.push_back(make_pair(l, make_pair(arr[i], arr[i - 1])));
  }
  sort(v.begin(), v.end());
  a = 0;
  k = 0;
  l = 0;
  while (1) {
    b += 2;
    if (a + b >= m) break;
    for (j = k; j < n - 1 && a + b < m; j++) {
      d = v[j].first - (2 * c) - 1;
      if (d <= 0)
        k++;
      else if (d == 1) {
        brr[l++] = v[j].second.second + c + 1;
        k++;
        a++;
        h += c + 1;
      } else {
        brr[l++] = v[j].second.second + c + 1;
        a++;
        h += c + 1;
        if (a + b < m) {
          brr[l++] = v[j].second.first - c - 1;
          a++;
          h += c + 1;
        } else
          break;
      }
    }
    c++;
  }
  d = m - a;
  e = d / 2;
  f = d % 2;
  for (i = 0; i < e; i++) {
    brr[l++] = arr[0] - i - 1;
    h += i + 1;
  }
  for (i = 0; i < e; i++) {
    brr[l++] = arr[n - 1] + i + 1;
    h += i + 1;
  }
  if (f) {
    brr[l++] = arr[n - 1] + e + 1;
    h += e + 1;
  }
  sort(brr, brr + l);
  printf("%lld\n", h);
  for (i = 0; i < l; i++) printf("%lld ", brr[i]);
}
