#include <fstream>
using namespace std;
const int NMAX = 301;

ifstream f("nunta.in");
ofstream g("nunta.out");
int n, act[NMAX] = {1, 1}, prec[NMAX] = {1, 1}, aux[NMAX];
void adaugare(int A[], int B[])
{
    int t = 0;
    for(int i = 1 ; i <= max(A[0], B[0]); i++)
    {
        t += A[i] + B[i];
        A[i] = t % 10;
        t /= 10;
    }
    while(t)
    {
        A[++A[0]] = t % 10;
        t /= 10;
    }
}

void copiere(int A[], int B[])
{
    for(int i = 0; i <= B[0]; i++)
        A[i] = B[i];
}

void afis()
{
    for(int i = act[0]; i >= 1; i--)
        g << act[i];
}

int main()
{
    f >> n;
    if(n <= 2)
    {
        g << n;
        return 0;
    }
    for(int i = 2; i <= n; i++)
    {
        copiere(aux, act);
        adaugare(act, prec);
        copiere(prec, aux);
    }
    afis();
    return 0;
}