View Compilation Error

0_0_25760456_9733.cpp: In function 'void update(long long int, int)':
0_0_25760456_9733.cpp:10:7: error: 'top' was not declared in this scope
   b[++top]=x%2;
       ^
0_0_25760456_9733.cpp:14:17: error: 'top' was not declared in this scope
   if(son[now][b[top]])now=son[now][b[top]];
                 ^