Compilare: main.cpp: In function 'void add(std::__cxx11::string, int)': main.cpp:27:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<s.size();i++) ~^~~~~~~~~ main.cpp:40:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(i+1==s.size()) ~~~^~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:135:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=1;i<t.size();i++) ~^~~~~~~~~ main.cpp:143:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=1;i<t.size();i++) ~^~~~~~~~~