Compilare: main.cpp: In function 'bool eval(std::__cxx11::string)': main.cpp:41:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 0; j < v[i].size(); j++) ~~^~~~~~~~~~~~~ main.cpp: In function 'void solve()': main.cpp:56:22: warning: unused variable 'i' [-Wunused-variable] for (const auto &i : v[n]) ^