View Compilation Error

0_0_29754230_30786.cpp: In function 'int main()':
0_0_29754230_30786.cpp:6:2: error: 'cin' was not declared in this scope
  cin>>n;
  ^
0_0_29754230_30786.cpp:13:30: error: 'pow' was not declared in this scope
    sum=sum+1.0/(i+1)*pow(-1,i);
                              ^
0_0_29754230_30786.cpp:15:23: error: 'printf' was not declared in this scope
   printf("%.2lf\n",sum);
                       ^