Compilare: user.cpp: In function ‘void dfs(int, int)’: user.cpp:16:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<v[x].size();++i) ^ user.cpp: In function ‘void dfs2(int, int)’: user.cpp:26:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<u[x].size();++i) ^ user.cpp: In function ‘void dfs3(int)’: user.cpp:39:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<v[x].size()&&!OK;++i) ^ user.cpp: In function ‘int main()’: user.cpp:76:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=0;j<v[i].size();++j) ^