func_code_string: #include <bits/stdc++.h>   using namespace std;   const int maxint = -1u >> 1;   int n;   long long x[100010];   bool v[100010];   int main() {     scanf( %d , &n);     for (int i = 0; i < n; i++) scanf( %I64d , &x[i]);     sort(x, x + n);     long long a = -1, b = -1;     long long ret = 0;     for (int i = n - 2; i >= 0; i--) {       if (v[i + 1]) continue;       if (x[i + 1] - x[i] <= 1) {         if (a == -1) {           a = x[i];           v[i] = true;         } else {           b = x[i];           v[i] = true;           ret += a * b;           a = -1;         }       }     }     cout << ret << endl;     return 0;   }   