View Compilation Error

0_0_38294038_16682.cpp: In function 'int main()':
0_0_38294038_16682.cpp:25:2: error: 'cin' was not declared in this scope
  cin>>t;
  ^
0_0_38294038_16682.cpp:45:3: error: 'cout' was not declared in this scope
   cout<<sum<<endl;
   ^
0_0_38294038_16682.cpp:45:14: error: 'endl' was not declared in this scope
   cout<<sum<<endl;
              ^