#include <fstream>
std::ifstream si("nunta.in");
std::ofstream so("nunta.out");
short a[1005],b[1005];
int main()
{
    int n,k;
    short x,t;
    si>>n;
    a[1]=b[1]=1;
    k=1;
    short nr;
    for(int i=2;i<=n;++i)
    {
        t=0;
        for(int j=1;j<=k;j++)
        {
            nr=b[j];
            x=a[j]+b[j]+t;
            b[j]=x%10;
            t=x/10;
            a[j]=nr;
        }
        if(t>0)
        {
            k++;
            b[k]=t;
        }
    }
    if(n==1)
        so<<1;
    else
        for(int i=k;i>0;--i)
        {
            so<<b[i];
        }
    return 0;
}