Compilare: user.cpp: In function ‘int bf()’: user.cpp:21:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0 ; i < L[a].size() ; i++){ ^ user.cpp: In function ‘int main()’: user.cpp:38:48: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf( f , "%d%d%d%d", &n , &m , &s , &d ); ^ user.cpp:40:55: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf( f , "%d%d%d%d" , &a , &b , &aa , &bb ); ^