View Compilation Error

0_0_28801922_29011.cpp: In function 'int main()':
0_0_28801922_29011.cpp:17:9: error: 'cin' was not declared in this scope
  while (cin >> M){
         ^
0_0_28801922_29011.cpp:18:3: error: 'cout' was not declared in this scope
   cout << getnum(M) << endl;
   ^
0_0_28801922_29011.cpp:18:24: error: 'endl' was not declared in this scope
   cout << getnum(M) << endl;
                        ^