View Compilation Error

0_0_37381022_1734.cpp: In function 'int main()':
0_0_37381022_1734.cpp:13:7: error: invalid types 'int[int]' for array subscript
    a[i]=a[i-1]+a[i-2];
       ^
0_0_37381022_1734.cpp:13:14: error: invalid types 'int[int]' for array subscript
    a[i]=a[i-1]+a[i-2];
              ^
0_0_37381022_1734.cpp:13:21: error: invalid types 'int[int]' for array subscript
    a[i]=a[i-1]+a[i-2];
                     ^
0_0_37381022_1734.cpp:14:22: error: invalid types 'int[int]' for array subscript
   printf("%d\n",a[sum]);
                      ^