View Compilation Error

0_0_23516807_25371.cpp: In function 'int main()':
0_0_23516807_25371.cpp:6:25: error: 'scanf' was not declared in this scope
     while(~scanf("%d",&n))
                         ^
0_0_23516807_25371.cpp:8:17: error: 'getchar' was not declared in this scope
         getchar();
                 ^
0_0_23516807_25371.cpp:12:21: error: 'gets' was not declared in this scope
             gets(str);
                     ^
0_0_23516807_25371.cpp:20:34: error: 'printf' was not declared in this scope
             printf("%d\n",count/2);
                                  ^