#include<bits/stdc++.h> using namespace std; int main(){ long long a,b,i,n,s[1000]; cin>>a>>b; n = b - a; for(i = 1;i <= n;i++){ if(i == 1){ s[1] = 1; }else if(i == 2){ s[2] = 2; }else{ s[i] = s[i - 1] + s[i - 2]; } } cout<<a[n]<<endl; }