func_code_string: #include <bits/stdc++.h>   using namespace std;   const long long MOD = 1000000007;   const double pi = 3.141593;   int main() {     ios::sync_with_stdio(false);     int n, t = 0, ans = 0;     map<int, int> m;     cin >> n;     for (int i = 0; i < 2 * n; i++) {       int x;       cin >> x;       m[x]++;       t++;       if (m[x] == 2) t -= 2;       ans = max(ans, t);     }     cout << ans;   }   