#include <iostream>
#include <fstream>

using namespace std;

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

long int f1, f2;

long int inm(long int a, long int b)
    {
        f1=a*0+b*1;
        f2=a*1+b*1;
    }

int main()
{
    long int n, a=1, b=1;
    f>>n;
    while(n>1)
    {
        inm(a, b);
        a=f1;
        b=f2;
        n--;
    }
    g<<f2;
}