Compilare: main.cpp: In function 'void genprefix()': main.cpp:12:14: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 12 | for(i=1;i<s.size();++i) | ~^~~~~~~~~ main.cpp: In function 'int main()': main.cpp:32:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 32 | for(j=1;j<s.size();++j) | ~^~~~~~~~~