Compilare: main.cpp: In function 'bool bfs()': main.cpp:34:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0;i<H.size();i++){ ~^~~~~~~~~ main.cpp: In function 'int main()': main.cpp:87:14: warning: unused variable 'c' [-Wunused-variable] int x,a,b,c; ^ main.cpp:77:32: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("negot.in","r",stdin); ^ main.cpp:78:34: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("negot.out","w",stdout); ^