View Compilation Error

2_34362_2961165_13657.cpp: In function 'int main()':
2_34362_2961165_13657.cpp:15:5: error: 'cin' was not declared in this scope
     cin>>T;
     ^
2_34362_2961165_13657.cpp:61:13: error: 'cout' was not declared in this scope
             cout<<"-1"<<endl;
             ^
2_34362_2961165_13657.cpp:61:25: error: 'endl' was not declared in this scope
             cout<<"-1"<<endl;
                         ^
2_34362_2961165_13657.cpp:63:13: error: 'cout' was not declared in this scope
             cout<<sum<<endl;
             ^
2_34362_2961165_13657.cpp:63:24: error: 'endl' was not declared in this scope
             cout<<sum<<endl;
                        ^