Compilare: user.cpp: In function ‘int main()’: user.cpp:15:7: warning: unused variable ‘x’ [-Wunused-variable] char x; ^ user.cpp:20:31: 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:21:35: warning: ignoring return value of ‘char* fgets(char*, int, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fgets(digits, sizeof digits, fin); ^