Compilare: user.cpp: In function ‘void df(int, int)’: user.cpp:18:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0 ; i < g[node].size() ; ++i) ^ user.cpp: In function ‘int main()’: user.cpp:69:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("lca.in" , "r" , stdin); ^ user.cpp:70:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("lca.out" , "w" , stdout); ^ user.cpp:73:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d" , &N , &Q); ^ user.cpp:77:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d" , &x); ^ user.cpp:88:28: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d" , &x , &y); ^