Compilare: main.cpp: In function 'std::string fill_between(std::string)': main.cpp:23:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 23 | for(int i=1;i<s.size();i++) | ~^~~~~~~~~ main.cpp: In function 'void construct_trie(int, std::string)': main.cpp:37:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 37 | for(int i=1;i<s.size();i++) | ~^~~~~~~~~ main.cpp:47:38: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 47 | while(0<=i-p[i]-1 && i+p[i]+1<s.size() && s[i+p[i]+1]==s[i-p[i]-1]) | ~~~~~~~~^~~~~~~~~