Compilare: user.cpp: In function ‘int main()’: user.cpp:123:7: warning: variable ‘start’ set but not used [-Wunused-but-set-variable] auto start = std::chrono::high_resolution_clock::now(); ^ user.cpp:139:7: warning: variable ‘end’ set but not used [-Wunused-but-set-variable] auto end = std::chrono::high_resolution_clock::now(); ^ user.cpp:112:23: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fin, "%d", &N); ^