View Compilation Error

0_0_18356199_10607.cpp: In function 'int main()':
0_0_18356199_10607.cpp:74:14: error: too few arguments to function 'void dfs(int, int)'
         dfs(1);
              ^
0_0_18356199_10607.cpp:41:6: note: declared here
 void dfs(int u,int pre)
      ^