Compilare: user.cpp: In function ‘void radix_sort(int*, int)’: user.cpp:19:44: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (unsigned long long exp = 1; exp < max_A; exp *= BASE) { ^ user.cpp: In function ‘int main()’: user.cpp:43:43: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(in, "%d%d%d%d", &N, &A, &B, &C); ^