func_code_string: #include <bits/stdc++.h>   using namespace std;   int a[1000005];   int main() {     int n;     while (cin >> n) {       for (int i = n; i >= 0; i--)         if (!a[i]) {           int mm = (1 << ((int)(log2(i) + 1))) - 1;           a[i] = mm ^ i;           a[mm ^ i] = i;         }       long long int ans = 0;       for (int i = 0; i <= n; i++) {         ans += a[i] ^ i;       }       cout << ans << endl;       for (int i = 0; i <= n; i++) {         cout << a[i];         if (i != n)           cout <<    ;         else           cout <<   n ;       }     }     return 0;   }   