#include <iostream>
using namespace std;
class A
{
public:
void func1() {}
void func2() {}
void func3() {}
};
class B
{
public:
void func1() {}
void func2() {}
void func3() {}
};
class C
{
public:
void func1() {}
void func2() {}
void func3() {}
};
int main()
{
cout << "Hello world!" << endl;
return 0;
}