Compilare: user.cpp: In function `int dfs1(int)': user.cpp:19: warning: comparison between signed and unsigned integer expressions user.cpp:26: warning: control reaches end of non-void function user.cpp: In function `int dfs2(int)': user.cpp:32: warning: comparison between signed and unsigned integer expressions user.cpp: In function `int main()': user.cpp:66: warning: int format, different type arg (arg 2)