Compilare: user.cpp: In function ‘void sieve()’: user.cpp:19:41: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 0; j < primes.size() && primes[j] <= low[i] && i * primes[j] < NMAX; ++ j) ^ user.cpp: In function ‘void process()’: user.cpp:61:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < cycle.size(); ++ i) { ^ user.cpp:77:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < cycle.size(); ++ i) ^