View Compilation Error

0_0_20316822_17367.cpp: In function 'int main()':
0_0_20316822_17367.cpp:6:24: error: 'scanf' was not declared in this scope
     while(scanf("%d",&a)==1)
                        ^
0_0_20316822_17367.cpp:14:32: error: 'printf' was not declared in this scope
         printf("%I64d\n",b[a-1]);
                                ^