func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     long long n, m;     long long a[100001];     long long b[100001];     cin >> n >> m;     for (int i = 0; i < n; i++) cin >> a[i];     sort(a, a + n);     long long x = 0, i = 1, count = 0;     while (m > 0) {       if (a[x] != i) {         if (m - i >= 0) {           m -= i;           b[count] = i;           count++;         } else           break;       } else         x++;       i++;     }     cout << count << endl;     for (int i = 0; i < count; i++) cout << b[i] <<    ;   }   