func_code_string: #include <bits/stdc++.h>   using namespace std;   inline long long isqrt(long long k) {     long long r = sqrt(k) + 1;     while (r * r > k) r--;     return r;   }   inline long long icbrt(long long k) {     long long r = cbrt(k) + 1;     while (r * r * r > k) r--;     return r;   }   inline long long mnz(long long& a, long long b) { return a = (a > b ? b : a); }   inline long long mxz(long long& a, long long b) { return a = (a < b ? b : a); }   inline string toString(long long n) {     stringstream ss;     ss << n;     return ss.str();   }   double const eps = 1e-6;   long long const Base = 1e9 + 7, oo = 1e17, MAXN = 1e6;   long long A[MAXN + 5];   vector<long long> dske[MAXN + 5];   bitset<MAXN + 5> bi;   long long Solves() {     long long n, m, k, cnt = 0, ans = 0, x = -1, y = -1, q, c, sum = 0, v, t = -1;     cin >> n;     for (long long i = 1; i <= n; i++) dske[i].clear(), bi[i] = 0;     for (long long i = 1; i <= n; i++) {       cin >> k;       c = 0;       while (k--) {         cin >> x;         if (!bi[x] and !c) c = x;       }       if (c)         bi[c] = 1;       else         y = i;     }     if (y == -1) return cout <<  OPTIMAL  << endl, 0;     vector<long long> vec;     for (long long i = 1; i <= n; i++)       if (!bi[i]) vec.push_back(i);     map<long long, long long> mm;     for (long long i = 0; i < dske[y].size(); i++) mm[dske[y][i]] = 1;     for (long long i = 0; i < vec.size(); i++) {       if (!mm[vec[i]]) {         cout <<  IMPROVE  << endl;         cout << y <<     << vec[i] << endl;         return 0;       }     }     assert(0);     return 0;   }   int main() {     if (fopen( locin.txt ,  r )) freopen( locin.txt ,  r , stdin);     ios_base::sync_with_stdio(0);     cin.tie(0);     cout.tie(0);     long long test = 1;     cin >> test;     for (long long T = 1; T <= test; T++) {       Solves();     }   }   