View Compilation Error

0_0_21993856_23355.cpp: In function 'int add(int, int)':
0_0_21993856_23355.cpp:51:40: error: too few arguments to function 'int copyNode(int)'
             _next[now][son] = copyNode() ;
                                        ^
0_0_21993856_23355.cpp:38:9: note: declared here
     int copyNode(int x){
         ^