View Compilation Error

0_0_24536426_22732.cpp: In function 'int main()':
0_0_24536426_22732.cpp:13:25: error: 'scanf' was not declared in this scope
     while(scanf("%d", &n) != EOF) {  
                         ^
0_0_24536426_22732.cpp:13:30: error: 'EOF' was not declared in this scope
     while(scanf("%d", &n) != EOF) {  
                              ^
0_0_24536426_22732.cpp:19:30: error: 'printf' was not declared in this scope
         printf("%d\n", cow(n));  
                              ^