Compilare: main.cpp: In function 'int main()': main.cpp:40:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 2; i <= n; i++) ~~^~~~ main.cpp:43:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 2; i <= n; i++) { ~~^~~~ main.cpp:47:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = i + i; j <= n; j += i) ~~^~~~