1031 骨牌覆盖

#include<iostream>
#include<algorithm>
using namespace std;
const int Mod = 1e9 + 7;
typedef long long ll;
ll f[1005] = {0, 1, 2};
int main(){
	int n;
	ios::sync_with_stdio(false);
	cin >> n;
	for(int i = 3; i <= n; ++i)
		f[i] = (f[i - 1] + f[i - 2]) % Mod;
	cout << f[n] << endl;
	return 0;
}