#include <cstdio>
#include <cstdlib>
#include <iostream>
#include <cstring>
#include <list>
#include <set>
#include <unordered_map>
#include <time.h>
#include <math.h>

using namespace std;

class A
{
    int i;

public:
    A(int ii = 0) : i(ii) {}
    void show() { cout << i << endl; }
};

class B
{
    int x;

public:
    B(int xx) : x(xx) {}
    operator A() const { return A(x); }
};

void g(A a)
{
    a.show();
}

int main()
{
    B b(10);
    g(b);
    g(20);
    return 0;
}