#include <fstream>

using namespace std;

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

long long d[1005][1005];
int i,n,m,j,t;

int main()
{
    fin >> n;
    d[1][1]=1;
    d[1][0]=1;
    d[2][1]=2;
    d[2][0]=1;
    for (i=3;i<=n;i++)
    {
        m=d[i-1][0];
        d[i][0]=m;
        for (j=1;j<=m;j++)
        {
            d[i][j]=d[i-1][j]+d[i-2][j]+t;
            t=d[i][j]/10;
            d[i][j]%=10;
        }
        if (t!=0)
        {
            d[i][0]++;
            d[i][d[i][0]]=t;
            t=0;
        }
    }
    for (i=d[n][0];i>=1;i--) fout << d[n][i];

    return 0;
}