Compilare: user.cpp: In function ‘int main(int, char**)’: user.cpp:39:8: warning: unused variable ‘next_end’ [-Wunused-variable] ull next_end = next_i * next_i; ^ user.cpp:26:23: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(i, "%d\n", &T); ^ user.cpp:28:31: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(i, "%d %d\n", &N, &R); ^