#include<cstdio>
using namespace std;
int n,a[256],b[256],c[256];
void adunare(int C[], int A[], int B[])
{
    int i,t=0;
    for (i=1;i<=A[0] || i<=B[0] || t;++i,t/=10)
        C[i]=(t+=A[i]+B[i])%10;
    C[0]=i-1;
}
void copiere(int B[], int A[])
{
    int i;
    for (i=0;i<=A[0];++i)
        B[i]=A[i];
}
int main()
{
    int i;
    freopen("nunta.in","r",stdin);
    freopen("nunta.out","w",stdout);
    scanf("%d",&n);
    a[0]=1;
    b[0]=1, b[1]=1;
    for (i=1;i<=n;++i)
    {
        adunare(c,a,b);
        copiere(a,b);
        copiere(b,c);
    }
    for (i=b[0];i>0;--i)
        printf("%d",b[i]);
    printf("\n");
    return 0;
}