View Compilation Error

0_0_21936538_2281.cpp: In function 'int main()':
0_0_21936538_2281.cpp:16:25: error: 'a' was not declared in this scope
             scanf("%d",&a[i]);
                         ^
0_0_21936538_2281.cpp:18:12: error: 'a' was not declared in this scope
         if(a[n-1]==2)
            ^