func_code_string: #include <bits/stdc++.h>   using namespace std;   long long n, a[1005];   map<long long, int> x;   int ans;   void f(long long a, long long b) {     long long cur = a + b;     vector<long long> q;     q.push_back(a);     q.push_back(b);     int len = 2;     x[a]--;     x[b]--;     while (x[cur] > 0) {       x[cur]--;       q.push_back(cur);       a = b;       b = cur;       cur = a + b;       len++;     }     ans = max(len, ans);     for (int i = 0; i < q.size(); i++) x[q[i]]++;   }   int main() {     cin >> n;     for (int i = 1; i <= n; i++) {       cin >> a[i];       x[a[i]]++;     }     ans = x[0];     for (int i = 1; i <= n; i++) {       for (int j = i + 1; j <= n; j++) {         if (a[i] == a[j] && a[i] == 0) continue;         f(a[i], a[j]);         f(a[j], a[i]);       }     }     cout << ans;   }   