Compilare: main.cpp: In function 'void insert(node*, std::__cxx11::string, int)': main.cpp:39:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<s.length();i++){ ~^~~~~~~~~~~ main.cpp: In function 'void check(node*, std::__cxx11::string, int)': main.cpp:81:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<s.length();i++){ ~^~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:117:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(l==0||start>=s.length()){ ~~~~~^~~~~~~~~~~~ main.cpp:132:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(l==0||start>=s.length()){ ~~~~~^~~~~~~~~~~~