Compilare: user.cpp: In function ‘int main()’: user.cpp:51:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < ans.size(); i++) { ^ user.cpp:21:29: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fin, "%d%d", &N, &M); ^ user.cpp:24:30: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fin, "%d%d", &x, &y); ^