Compilare: user.cpp: In function ‘bool cmp(std::string, std::string)’: user.cpp:40:40: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<min(a.size(),b.size());++i) ^ user.cpp: In function ‘void query(std::string)’: user.cpp:77:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<a.size();++i) ^ user.cpp: In function ‘int main()’: user.cpp:128:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=0;j<x.size();++j) ^