Compilare: user.cpp: In function ‘int DFS(int)’: user.cpp:17:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i = 0 ; i < v[elem].size(); i++) ^ user.cpp:25:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i = 0; i < v[elem].size(); i++) ^ user.cpp:31:1: warning: no return statement in function returning non-void [-Wreturn-type] } ^ user.cpp: In function ‘int main()’: user.cpp:39:17: warning: unused variable ‘j’ [-Wunused-variable] int i , j , a , b; ^