#include <bits/stdc++.h>
using namespace std;
string add(string a,string b){
    int la = a.size(),lb=b.size(),l=max(la,lb);
    while(a.size()<=l)a = '0' + a;
    while(b.size()<=l)b = '0' + b;
    string c="";
    int nxt=0,tmp=0;
    for(int i = l;i>=0;i--){
        tmp = nxt + a[i] - '0' + b[i] - '0';
        nxt = tmp / 10,tmp = tmp % 10;
        c = (char)(tmp + '0') + c;
    }
    return c;
}
int n,m;
string F(int x){
    string a="1",b="1",c;
    if(n == 1 || n == 2)return "1";
    x--;
    while(x--){
        c=add(b,a);
        a=b;
        b=c;
    }
    while(c[0]=='0')c.erase(0,1);
    return c;
}
int main(){
    cin >> m >> n;
    cout << F(n-m);
    return 0;
}