View Compilation Error

0_0_29030586_18993.cpp: In function 'int main()':
0_0_29030586_18993.cpp:52:11: error: 'cin' was not declared in this scope
     while(cin>>num&&num!=0)
           ^
0_0_29030586_18993.cpp:62:35: error: 'sort' was not declared in this scope
         sort(sticks,sticks+num,cmp);
                                   ^
0_0_29030586_18993.cpp:71:17: error: 'cout' was not declared in this scope
                 cout<<l<<endl;
                 ^
0_0_29030586_18993.cpp:71:26: error: 'endl' was not declared in this scope
                 cout<<l<<endl;
                          ^