Compilare: user.cpp: In function ‘long long unsigned int calc_2(long long unsigned int, long long unsigned int)’: user.cpp:43:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 1; i <= n; i++) ^ user.cpp: In function ‘int main()’: user.cpp:65:40: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fin, "%d %d %d", &p, &n, &u); ^