Compilare: user.cpp: In function ‘int compare(std::string, std::string)’: user.cpp:14:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(a<x.size()&&x[a]==y[a])a++; ^ user.cpp: In function ‘bool common(std::string, std::string)’: user.cpp:24:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<x.size(); i++){ ^ user.cpp:25:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(found<y.size()){ ^ user.cpp:31:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(found==y.size())return true; ^ user.cpp: In function ‘int main()’: user.cpp:41:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(v[i].size()>mx){ ^ user.cpp:44:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] }else if(v[i].size()==mx){ ^