Compilare: main.cpp: In function 'void initialise_sieve(std::vector<bool>&)': main.cpp:279:34: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<bool>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 279 | for (ll j = 2; j * i < lt(prime_sieve); j++) | ^ main.cpp: In function 'int main()': main.cpp:360:10: warning: variable 'start' set but not used [-Wunused-but-set-variable] 360 | auto start = std::chrono::high_resolution_clock::now(); | ^~~~~