Compilare: main.cpp: In function 'int union_sets(int, int)': main.cpp:38:1: warning: no return statement in function returning non-void [-Wreturn-type] } ^ main.cpp: In function 'int main()': main.cpp:55:41: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < m && sol.size() < n; i++) ~~~~~~~~~~~^~~ main.cpp:45:34: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("apm.in", "r", stdin); ^ main.cpp:46:36: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("apm.out", "w", stdout); ^