#include <bits/stdc++.h>
using namespace std;
long long mod=998244353;
int main(){
    int N,M; cin>>N>>M;
    if(N>M){cout<<1<<endl; return 0;}
    if(N==M){cout<<2<<endl; return 0;}
    int count=M-N;
    vector<long long>ans(count+3);
    ans[0]=1;
    ans[1]=1;
    ans[2]=2;
    for(int i=3;i<count+3;i++){ans[i]=ans[i-1]+ans[i-2];ans[i]%mod;}
    cout<<ans[count+2]<<endl;
}