Compilare: main.cpp: In function 'void ciur()': main.cpp:24:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0; j < prime.size() && i * prime[j] <= 1e6; ++j) { ~~^~~~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:53:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < prime.size() && 1LL * prime[i] * prime[i] <= n; ++i) { ~~^~~~~~~~~~~~~~