View Code of Problem 23

#include<iostream>
#include<vector>
#include<algorithm>
#include<iomanip>
#include<string>

using namespace std;

int main()
{
	int M;


	while (cin >> M) {

		if (M == 0)
			break;

		long long small = 0;
		long long big = 1;

		long long sum = 1;
		while (M - 1) {

			M--;

			long long temp = small;	//即将变成大白兔的小白兔数量

			small = big;	//生下小白兔

			big += temp;	//长成大白兔
			
			sum = big + small;
		}

		cout << sum << endl;
	}

}