Compilare: main.cpp: In function 'void BFS(int)': main.cpp:4:40: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] #define REP(i, a, b) for (int i = a; i <= b; i++) main.cpp:24:7: REP(i, 0, graph[x].size()-1) ~~~~~~~~~~~~~~~~~~~~~~~ main.cpp:24:3: note: in expansion of macro 'REP' REP(i, 0, graph[x].size()-1) ^~~ main.cpp: In function 'int main()': main.cpp:35:31: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("bfs.in", "r", stdin); ^ main.cpp:36:33: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("bfs.out", "w", stdout); ^