#include<fstream.h>

long a[1001],b[1001],c[1001],i,j,k,n,t,s;

int main()
{
ifstream f("nunta.in");
ofstream g("nunta.out");
f>>n;
a[0]=1;b[0]=1;
a[1]=1;b[1]=1;
for (k=1;k<n;k++)
    {
    t=0;
    for (i=1;i<=b[0];i++)
        {
        s=b[i]+a[i]+t;
        t=s/10;
        c[i]=s%10;
        }
    c[0]=b[0];
    if (t>0) c[++c[0]]=t;
    for (i=0;i<=b[0];i++)
        a[i]=b[i];
    for (i=0;i<=c[0];i++)
        b[i]=c[i];
    }
for (i=b[0];i>=1;i--)
    g<<b[i];
g<<'\n';
g.close();
return 0;
}