Compilare: user.cpp: In function ‘int df(int)’: user.cpp:16:37: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < vec[p].size(); i++) ^ user.cpp: In function ‘int main()’: user.cpp:36:24: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fi, "%d\n", &n); ^ user.cpp:45:38: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fi, "%d %d\n", &a, &b); ^