func_code_string: #include <bits/stdc++.h>   using namespace std;   long long int a[1001];   map<long long int, int> used;   int ans = 0;   map<pair<long long int, long long int>, bool> us;   void rec(long long int x, long long int y, int kol) {     ans = max(ans, kol);     long long int z = x + y;     if (z > 1000000000 || z < -1000000000) return;     x = y;     y = z;     if (used[z] > 0) {       used[z]--;       rec(x, y, kol + 1);       used[z]++;     }   }   int main() {     int n;     cin >> n;     for (int i = 1; i <= n; ++i) {       cin >> a[i];       used[a[i]]++;     }     for (int i = 1; i <= n; ++i) {       for (int j = 1; j <= n; ++j) {         if (us[make_pair(a[i], a[j])] || i == j) continue;         us[make_pair(a[i], a[j])] = true;         used[a[i]]--;         used[a[j]]--;         rec(a[i], a[j], 2);         used[a[i]]++;         used[a[j]]++;       }     }     cout << ans << endl;     return 0;   }   