/in/foo.cc: In function 'int main()':
/in/foo.cc:5:4: error: 'cout' was not declared in this scope
    cout<<"Please input two number x and y(0<=x,y<=327767)"<<endl;
    ^~~~
/in/foo.cc:5:61: error: 'endl' was not declared in this scope
    cout<<"Please input two number x and y(0<=x,y<=327767)"<<endl;
                                                             ^~~~
/in/foo.cc:8:5: error: 'cin' was not declared in this scope
     cin>>a>>b;
     ^~~
/in/foo.cc:11:4: error: expected ';' before 'int'
    int sum;
    ^~~