View Compilation Error

0_0_32718590_15662.cpp: In function 'int main()':
0_0_32718590_15662.cpp:8:18: error: 'scanf' was not declared in this scope
     scanf("%d",&n);
                  ^
0_0_32718590_15662.cpp:9:13: error: 'getchar' was not declared in this scope
     getchar();
             ^
0_0_32718590_15662.cpp:16:39: error: 'printf' was not declared in this scope
             case '+':printf("%d\n",A+B);
                                       ^