View Compilation Error

0_0_21378548_25618.cpp: In function 'int main()':
0_0_21378548_25618.cpp:5:9: error: 'in' was not declared in this scope
         in a[18]={9,1,4,9,4,2,9,7,1,9,1,5,9,4,7,9,7,8};
         ^
0_0_21378548_25618.cpp:10:23: error: 'a' was not declared in this scope
                 cout<<a[n]<<endl;
                       ^