View Compilation Error

0_0_20227586_23146.cpp: In function 'int main()':
0_0_20227586_23146.cpp:5:1: error: 'cin' was not declared in this scope
 cin<<a;
 ^
0_0_20227586_23146.cpp:13:11: error: 'cout' was not declared in this scope
 if(i%2==0)cout<<"first"<<endl;
           ^
0_0_20227586_23146.cpp:13:26: error: 'endl' was not declared in this scope
 if(i%2==0)cout<<"first"<<endl;
                          ^
0_0_20227586_23146.cpp:14:6: error: 'cout' was not declared in this scope
 else{cout<<"second"<<endl;}
      ^
0_0_20227586_23146.cpp:14:22: error: 'endl' was not declared in this scope
 else{cout<<"second"<<endl;}
                      ^