View Compilation Error

0_0_34610387_24098.cpp: In function 'int main()':
0_0_34610387_24098.cpp:18:25: error: 'n' was not declared in this scope
     while (scanf("%d", &n) != EOF && n)
                         ^
0_0_34610387_24098.cpp:26:25: error: 'a' was not declared in this scope
             scanf("%s", a[i]);
                         ^