Compilare: main.cpp: In function 'int main()': main.cpp:42:54: warning: comparison of integer expressions of different signedness: '__gnu_cxx::__alloc_traits<std::allocator<int>, int>::value_type' {aka 'int'} and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 42 | if(st[j].top() != -1 and st[j].top() <= s[j].size() and mat[j][st[j].top()][ceva[0] - 'a']){ | ~~~~~~~~~~~~^~~~~~~~~~~~~~