View Compilation Error

0_0_18866703_1690.cpp: In function 'int main()':
0_0_18866703_1690.cpp:6:15: error: 'scanf' was not declared in this scope
  scanf("%d",&n);
               ^
0_0_18866703_1690.cpp:7:10: error: 'getchar' was not declared in this scope
  getchar();
          ^
0_0_18866703_1690.cpp:11:9: error: 'gets' was not declared in this scope
   gets(a);
         ^
0_0_18866703_1690.cpp:12:28: error: 'printf' was not declared in this scope
   printf("String #%d\n",z++);
                            ^
0_0_18866703_1690.cpp:13:19: error: 'strlen' was not declared in this scope
   while(x<strlen(a))
                   ^
0_0_18866703_1690.cpp:20:9: error: 'puts' was not declared in this scope
   puts(a);
         ^