Compilare: main.cpp: In function 'void Insert(std::__cxx11::string)': main.cpp:24:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int i = 0; i < s.size(); ++i ) { ~~^~~~~~~~~~ main.cpp: In function 'int LongestSubstring(std::__cxx11::string)': main.cpp:40:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int i = 0; i < s.size(); ++i ) { ~~^~~~~~~~~~ main.cpp: In function 'void Delete(std::__cxx11::string)': main.cpp:62:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int i = 0; i < s.size(); ++i ) { ~~^~~~~~~~~~ main.cpp: In function 'int Count(std::__cxx11::string)': main.cpp:87:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int i = 0; i < s.size(); ++i ) { ~~^~~~~~~~~~