Compilare: user.cpp: In function ‘void dfs(int)’: user.cpp:12:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<a[nod].size();++i){ ^ user.cpp: In function ‘int main()’: user.cpp:19:17: warning: unused variable ‘start’ [-Wunused-variable] int n,m,x,y,start,e=0; ^