Compilare: user.cpp: In constructor ‘Persistent_UnionFind::Persistent_UnionFind(int, int)’: user.cpp:112:28: warning: ‘Persistent_UnionFind::Stack’ will be initialized after [-Wreorder] vector<pair<int, int>> Stack; ^ user.cpp:109:17: warning: ‘std::vector<int> Persistent_UnionFind::color’ [-Wreorder] vector<int> color, sum; ^ user.cpp:14:5: warning: when initialized here [-Wreorder] Persistent_UnionFind(const int n, const int nr_q) : nrComponents(0), Parent(vector<int>(n + 1)), Size(vector<int>(n + 1)), ^ user.cpp: In function ‘int main()’: user.cpp:357:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (i < edges.size()) ^ user.cpp:361:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (j < edges.size() && edges[i].c == edges[j].c) ^ user.cpp:377:60: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (DSU.getSum(white.back()) == white.size()) ^ user.cpp:245:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("unlock.in", "r", stdin); ^ user.cpp:246:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("unlock.out", "w", stdout); ^ user.cpp: In function ‘char getChar()’: user.cpp:126:45: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread(buffer, BUFFER_SIZE, 1, stdin); ^