Compilare: user.cpp: In function ‘int dfs(int)’: user.cpp:20: warning: comparison between signed and unsigned integer expressions user.cpp:26: warning: no return statement in function returning non-void user.cpp: In function ‘int dfs2(int)’: user.cpp:34: warning: comparison between signed and unsigned integer expressions user.cpp:39: warning: no return statement in function returning non-void user.cpp: In function ‘int main()’: user.cpp:67: warning: comparison between signed and unsigned integer expressions