#include<iostream>
#include<fstream>

using namespace std;

ifstream f("nunta.in");
ofstream g("nunta.out");


int main ()
{
    int a,b,c,n;

    a=1;
    b=2;


    f>>n;

 if(n==1)cout<<"1";
 if(n==2)cout<<"2";
    for(int i=3;i<=n;i++)
    {
        c=a+b;
        a=b;
        b=c;
        }

      g<<b<<" ";


}