View Compilation Error

0_0_34258501_29839.cpp: In function 'int main()':
0_0_34258501_29839.cpp:6:21: error: 'scanf' was not declared in this scope
  while(scanf("%d",&n),n){
                     ^
0_0_34258501_29839.cpp:27:22: error: 'printf' was not declared in this scope
   printf("%d\n",c1[n]);
                      ^