func_code_string: #include <bits/stdc++.h>   using namespace std;   const string yno[2] = { NO n ,  YES n };   int dem(vector<int> &a, int k) {     return upper_bound(a.begin(), a.end(), k) -            lower_bound(a.begin(), a.end(), k);   }   int dem(long long k) {     int ans = 0;     while (k) {       ans += k & 1;       k >>= 1;     }     return ans;   }   void process() {     int n, m;     cin >> n >> m;     vector<int> a(n), b(m);     for (int &i : a) cin >> i;     for (int &i : b) cin >> i;     vector<pair<long long, long long> > c;     map<int, pair<long long, long long> > M;     for (int i = 0; i <= n - 1; i++) {       for (int j = 0; j <= m - 1; j++) {         M[a[i] + b[j]].first |= (1ll << i);         M[a[i] + b[j]].second |= (1ll << j);       }     }     for (auto it = M.begin(); it != M.end(); it++) {       c.push_back(it->second);     }     int ans = 0;     for (int i = 0; i < c.size(); i++) {       for (int j = i; j < c.size(); j++) {         ans = max(ans, __builtin_popcountll(c[i].first | c[j].first) +                            __builtin_popcountll(c[i].second | c[j].second));       }     }     cout << ans;   }   int main() {     ios_base::sync_with_stdio(false);     cin.tie(0);     process();     return 0;   }   