Compilare: main.cpp: In function 'bool bfs()': main.cpp:66:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<g[u].size(); i++) { ~^~~~~~~~~~~~ main.cpp: In function 'int dfs(int, int)': main.cpp:80:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(; ptr[u] < g[u].size(); ptr[u]++) { ~~~~~~~^~~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:138:34: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("sakura.in", "r", stdin); ^ main.cpp:139:36: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("sakura.out", "w", stdout); ^