Compilare: user.cpp: In function ‘int main()’: user.cpp:19:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(d * d <= n && n) ^ user.cpp:12:24: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f, "%d", &n); ^