View Compilation Error

0_0_18771181_5439.cpp: In function 'int main()':
0_0_18771181_5439.cpp:23:24: error: 'scanf' was not declared in this scope
     while(scanf("%d",&n))
                        ^
0_0_18771181_5439.cpp:35:29: error: 'printf' was not declared in this scope
             printf("%d",a[i]);  
                             ^
0_0_18771181_5439.cpp:36:25: error: 'printf' was not declared in this scope
         printf("%d",a[0]);
                         ^