Compilare: main.cpp: In function 'void calc_z(std::string&)': main.cpp:14:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 14 | for(int i=1; i<s.size(); i++) | ~^~~~~~~~~ main.cpp:20:43: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 20 | while(s[z[i]]==s[i+z[i]] && i+z[i]<s.size()) | ~~~~~~^~~~~~~~~ main.cpp: In function 'int main()': main.cpp:45:17: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 45 | while(dr<s.size()-2*len) | ~~^~~~~~~~~~~~~~~