Compilare: main.cpp: In function 'int solve()': main.cpp:13:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 13 | for(int i=1; i<=book.size(); i++){ | ~^~~~~~~~~~~~~ main.cpp:16:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 16 | for(int i=1; i<res.size(); i++){ | ~^~~~~~~~~~~ main.cpp:18:25: warning: comparison of integer expressions of different signedness: 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare] 18 | if(w.size() > i) continue; | ~~~~~~~~~^~~