View Compilation Error

0_0_25830582_10601.cpp: In function 'int main()':
0_0_25830582_10601.cpp:91:36: error: 'ind' was not declared in this scope
                     if(tail[u]->a==ind)tail[u]->a=NULL;
                                    ^
0_0_25830582_10601.cpp:108:36: error: 'ind' was not declared in this scope
                     if(head[u]->a==ind)head[u]->a=NULL;
                                    ^