View Compilation Error

0_0_28997527_31467.cpp: In function 'void dfs(int, int)':
0_0_28997527_31467.cpp:29:20: error: too few arguments to function 'void dfs(int, int)'
             dfs(x.v);
                    ^
0_0_28997527_31467.cpp:20:13: note: declared here
 inline void dfs(int u,int pre){
             ^