Compilare: main.cpp: In function 'void maxi(std::__cxx11::string)': main.cpp:15:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<x.size(); i++) ~^~~~~~~~~ main.cpp: In function 'int main()': main.cpp:32:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<s.size(); i++) ~^~~~~~~~~ main.cpp:31:17: warning: unused variable 'i' [-Wunused-variable] int i=0; ^