Compilare: main.cpp: In function 'void dfs(int)': main.cpp:29:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<g[start_node].size(); i++) ~^~~~~~~~~~~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:50:37: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("domino.in", "r", stdin); ^ main.cpp:51:39: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("domino.out", "w", stdout); ^ main.cpp:54:20: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^ main.cpp:58:30: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &x, &y); ^