View Compilation Error

0_0_33108961_21950.cpp: In function 'int main()':
0_0_33108961_21950.cpp:20:23: error: 'scanf' was not declared in this scope
  while(~scanf("%d", &k) && k){
                       ^
0_0_33108961_21950.cpp:21:27: error: 'printf' was not declared in this scope
   printf("%d\n", search(k));
                           ^