View Compilation Error

0_0_14693104_16420.cpp: In function 'int main()':
0_0_14693104_16420.cpp:29:50: error: 'a' was not declared in this scope
         for (int i = 1;i <= n;i ++) scanf("%d", &a[i]);
                                                  ^
0_0_14693104_16420.cpp:42:21: error: 'a' was not declared in this scope
             int x = a[i];
                     ^