#include <iostream>

using namespace std;

struct virtual_base {
    double data;
    virtual_base() {}
    virtual ~virtual_base() {}
};

struct non_virtual_base {
    double data;
    non_virtual_base() {}
    ~non_virtual_base() {}
};

int main() {
    std::cout << sizeof( virtual_base ) - sizeof( non_virtual_base ) << '\n';
    return 0;
}