View Compilation Error

0_0_16242971_10591.cpp: In function 'int main()':
0_0_16242971_10591.cpp:13:12: error: 'cas' was not declared in this scope
     while (cas--) {
            ^
0_0_16242971_10591.cpp:27:9: error: 'cout' was not declared in this scope
         cout<<ans<<endl;
         ^
0_0_16242971_10591.cpp:27:20: error: 'endl' was not declared in this scope
         cout<<ans<<endl;
                    ^