#include<bits/stdc++.h>

using namespace std;

long long a [5000]

#include<bits/stdc++.h>
using namespace std;
long long a[5000];
int qi,jie,zhenjie;
int main(){
	cin>>qi>>jie;
	a[0]=1;
	a[1]=1 ;
	for(int i=2;i<=1002;++i) a[i]=a[i-1]+a[i-2];
 	zhenjie=jie-(qi-1);
 	cout<<a[zhenjie-1];
	
    return 0;
}

;

int qi,jie,zhenjie;

int main(){

cin>>qi>>jie;

a[ 0 ]=1;

a[ 1 ]=1 ;

for(int i=2;i<=1002;++i) a[i]=a[i-1]+a[i-2];

zhenjie=jie-(qi-1);

cout<<a[zhenjie-1];

    return 0;

}