Compilare: main.cpp: In function 'void dfs(std::vector<std::vector<int> >&, std::vector<int>&, int, int)': main.cpp:9:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<arcs[currentNode].size(); ++i) ~^~~~~~~~~~~~~~~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:17:34: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("dfs.in", "r", stdin); ^ main.cpp:18:36: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("dfs.out", "w", stdout); ^ main.cpp:21:23: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &n, &m); ^ main.cpp:26:24: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &x, &y); ^