Compilare: main.cpp: In member function 'void DisjointSets::show()': main.cpp:54:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < parent.size(); i++) ~~^~~~~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:77:39: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("disjoint.in", "r", stdin); ^ main.cpp:78:41: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("disjoint.out", "w", stdout); ^