View Compilation Error

0_0_30004548_12912.cpp:4:15: error: conflicting declaration 'int a'
 int a[100001],a,b;
               ^
0_0_30004548_12912.cpp:4:5: note: previous declaration as 'int a [100001]'
 int a[100001],a,b;
     ^
0_0_30004548_12912.cpp: In function 'int main()':
0_0_30004548_12912.cpp:23:20: error: invalid types 'int [100001][int [100001]]' for array subscript
             indeg[a]++;
                    ^