Compilare: user.cpp: In function ‘int main()’: user.cpp:45:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0; j <= prim.size() && prim[j] * prim[j] <= val; ++ j){ ^ user.cpp:63:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0; j < Div[1].size(); ++ j) ^ user.cpp:68:40: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int k = 0; k < Div[j].size(); ++ k){ ^ user.cpp:73:52: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int l = 0; l < Div[i].size(); ++ l){ ^ user.cpp:67:13: warning: unused variable ‘val’ [-Wunused-variable] int val = v[j]; ^