Во такой код:

#include <iostream>
int Add (int x, int y)
{
    std::cout << "In Add(), received " << first << " and " << second << endl;
    return (first + seconds);
}

int main ()
{
    using std::cout;
    using std::cin;


    cout << "I'm in main ()!\n";
    int a, b, c;
    cout << "Enter two numbers: ";
    cin >> a;
    cin >> b;
    cout << "\nCalling Add()\n";
    c=Add(a, b);
    cout << "\nBack in main().\n";
    cout << "c was set to " << c;
    cout << "\nExiting...\n\n";
    return 0;
}

Компилятор выдает следующие ошибки:

C:\Program Files\Microsoft Visual Studio\MyProjects\sum\sum.cpp(4) : error C2065: 'first' : undeclared identifier
C:\Program Files\Microsoft Visual Studio\MyProjects\sum\sum.cpp(4) : error C2065: 'second' : undeclared identifier
C:\Program Files\Microsoft Visual Studio\MyProjects\sum\sum.cpp(4) : error C2065: 'endl' : undeclared identifier
C:\Program Files\Microsoft Visual Studio\MyProjects\sum\sum.cpp(5) : error C2065: 'seconds' : undeclared identifier