#include<iostream>
#include<fstream>

using namespace std;
ifstream fin("kfib.in");
ofstream fout("kfib.out");

int n;

void citire()
{
    fin>>n;
}

int fib(int k)
{
    if(k==1 || k==0)
    {
        return k;
    }
    else
    {
        return fib(k-1)+fib(k-2);
    }
}

int main ()
{
    citire();
    fout<<fib(n);
    fin.close();
    fout.close();
    return 0;
}