View Compilation Error

0_0_17283075_11057.cpp: In function 'int main()':
0_0_17283075_11057.cpp:9:5: error: 'cin' was not declared in this scope
     cin>>cas;
     ^
0_0_17283075_11057.cpp:44:9: error: 'cout' was not declared in this scope
         cout<<endl;
         ^
0_0_17283075_11057.cpp:44:15: error: 'endl' was not declared in this scope
         cout<<endl;
               ^