Compilare: user.cpp: In function ‘void ins()’: user.cpp:30:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(idx=0;idx<a.size();idx++) ^ user.cpp: In function ‘void match_it()’: user.cpp:65:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<s.size();i++) ^ user.cpp: In function ‘void update()’: user.cpp:80:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=0;j<node->l.size();j++) ^