View Compilation Error

0_0_30310052_20160.cpp: In function 'int32_t main()':
0_0_30310052_20160.cpp:23:23: error: 'a' was not declared in this scope
         fo(i,1,n)scan(a[i]);
                       ^
0_0_30310052_20160.cpp:5:33: note: in definition of macro 'scan'
 #define scan(n) scanf("%lld", &(n))
                                 ^
0_0_30310052_20160.cpp:26:23: error: 'a' was not declared in this scope
             int x=abs(a[i]);
                       ^