func_code_string: #include <bits/stdc++.h>   using namespace std;   const int kMaxN = 100010;   const int kMaxA = 1000000010;   int a[kMaxN];   signed main() {     cin.tie(0);     ios::sync_with_stdio(false);     long long n;     cin >> n;     for (long long i = 0; i < n; i++) {       cin >> a[i];     }     sort(a, a + n);     long long ans = 0;     for (long long x = 1; (1LL << x) < 2 * kMaxA; x++) {       long long val = (1 << x);       for (long long i = 0; i < n; i++) {         long long num = upper_bound(a + i + 1, a + n, val - a[i]) -                         lower_bound(a + i + 1, a + n, val - a[i]);         ans += num;       }     }     cout << ans << endl;     return 0;   }   