Compilare: main.cpp: In function 'void bf(int)': main.cpp:27:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (j=0;j<a[x].size();j++) ~^~~~~~~~~~~~ main.cpp: In function 'void read()': main.cpp:13:25: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d",&n,&m); ^ main.cpp:15:29: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d",&x,&y); ^ main.cpp: In function 'int main()': main.cpp:37:32: 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:38:34: 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); ^