#include<bits/stdc++.h>
using namespace std;
int nlessm;
int number()
{
	int a=0,b=1,c=1;
	for(int i=1;i<=nlessm;i++)
	{
		a=b;
		b=c;
		c=a+b;
	}
	return c;
}
int main()
{
	int m,n;
	cin >> m >> n;
	nlessm=m-n;
	cout << number();
	return 0;
}

求助大佬！！！