View Compilation Error

0_0_15871089_30650.cpp: In function 'int main()':
0_0_15871089_30650.cpp:28:1: error: 'cin' was not declared in this scope
 cin>>t;
 ^
0_0_15871089_30650.cpp:53:6: error: 'cout' was not declared in this scope
      cout<<sum-num<<endl;
      ^
0_0_15871089_30650.cpp:53:21: error: 'endl' was not declared in this scope
      cout<<sum-num<<endl;
                     ^