Compilare: main.cpp: In function 'int main()': main.cpp:26:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 26 | for(int j=0;j<prime.size() && prime[j] * prime[j] <= x ;j++) | ~^~~~~~~~~~~~~ main.cpp:40:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 40 | for(int j=0;j<prime.size() && prime[j] * prime[j] <= a ;j++) | ~^~~~~~~~~~~~~