View Compilation Error

0_0_25094324_25981.cpp: In function 'int main()':
0_0_25094324_25981.cpp:6:21: error: 'scanf' was not declared in this scope
  while(scanf("%d",&n)!=0)
                     ^
0_0_25094324_25981.cpp:23:21: error: 'printf' was not declared in this scope
   printf("%s\n",a[i]);
                     ^