#include <iostream>
#include <fstream>
using namespace std;

ifstream fin ("nunta.in");
ofstream fout ("nunta.out");

typedef int huge[225];
int n;
huge x1, x2, x3;

void aduna(huge a, huge b)
{
    int i, t=0;
    for (i=1; i<=a[0] || i<=b[0] || t; i++, t/=10)
    {
        if (i > a[0]) a[i]=0;
        if (i > b[0]) b[i]=0;
        a[i]=(t+=a[i]+b[i])%10;
    }
    a[0]=i-1;
}

void copie(huge a, huge b)
{
    for (int i=0; i<=b[0]; i++)
        a[i]=b[i];
}

int main()
{
    ios_base::sync_with_stdio(false);
    int i;
    fin >> n;
    if(n==1)
    {
        printf("1\n");
        return 0;
    }
    x1[0]=x1[1]=x2[0]=x2[1]=1;
    for(i=1; i<n; i++)
    {
        copie(x3, x2);
        aduna(x2, x1);
        copie(x1, x3);
    }
    for (i=x2[0]; i; i--)
        fout << x2[i];
    fin.close();
    fout.close();
    return 0;
}