hdoj：2045

#include <iostream>
using namespace std;
long long a[];

int main()
{
    int n;
    a[] = ;
    a[] = ;
    a[] = ;
    for (int i = ; i <= ; i++)
    {
        a[i] = a[i - ] +  * a[i - ];
    }
    while (cin >> n)
    {
        cout << a[n] << endl;
    }
}