func_code_string: #include <bits/stdc++.h>   using namespace std;   const long long int mxn = 1e5 + 1;   string s, s1, s2, s3;   char ch[10000][10000];   int main() {     long long int n, m, i, z, j, a = 0, ans = 0, k = 0, cnt = 0, b;     long long int c = 0, x, y, d = 0, sum = 0, mn = INT_MAX, mx = 0;     string ss, strn;     char ch;     cin >> n;     long long int evn[n + 1], odd[n + 1], e = 0, o = 0;     long long int ara[n + 2], bra[n + 1], cra[n + 1];     map<long long int, long long int> mp;     set<long long int> st;     set<long long int>::iterator sit;     priority_queue<long long int> pq;     for (i = 1; i <= n; i++) {       cin >> ara[i];     }     sort(ara + 1, ara + n + 1);     for (i = n; i > 1; i--) {       x = abs(ara[i] - ara[i - 1]);       if (x <= 1) {         if (!cnt) a = ara[i - 1];         if (cnt == 1) b = ara[i - 1];         cnt++;         if (cnt == 2) {           ans += (a * b);           cnt = 0;         }         --i;       }     }     cout << ans << endl;     return 0;   }   