Compilare: main.cpp: In function 'void dfs(int, int)': main.cpp:49:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < graph[u].size(); ++i) { ~~^~~~~~~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:58:37: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("radare.in", "r", stdin); ^ main.cpp:59:39: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("radare.out", "w", stdout); ^