Compilare: user.cpp: In function ‘void back_track(int, int, int)’: user.cpp:22:48: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int it = 0; it < Edge[ pos ].size(); it ++ ) { ^ user.cpp: In function ‘int main()’: user.cpp:48:42: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf( input_file, "%d %d", &N, &M ); ^ user.cpp:52:45: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf( input_file, "%d", &A[i][j] ); ^