C++ 代码
#include<iostream>
#include<cstdio>
#include<cstring>
using namespace std;
int n;
int ans;
void f(int k)
{
if(k == n) ans ++;
else if( k < n)
{
f(k + 1);
f(k + 2);
}
}
int main()
{
cin >> n;
f(0);
cout << ans << endl;
return 0;
}