View Compilation Error

0_0_38359186_8008.cpp: In function 'int add_char(char, int)':
0_0_38359186_8008.cpp:17:55: error: 'pre' was not declared in this scope
  int c=ch-'a'+1,z=new_state(maxl[u]+1,-1,NULL,-1),v=u;pre[z]=1;
                                                       ^