#include<bits/stdc++.h>
using namespace std;
short n;
char a[210],b[210],aux;
int main()
{
    freopen("nunta.in","r",stdin);
    freopen("nunta.out","w",stdout);
    scanf("%d",&n);
    n++;
    a[0]=1;
    a[1]=1;
    b[0]=1;
    b[1]=1;
    if(n==1 || n==2)
    {
        printf("1\n");
        return 0;
    }
    for(int t1=3;t1<=n;t1++)
    {
        int t=0,i;
        for(i=1;i<=a[0] || i<=b[0] || t;i++)
        {
            t=t+a[i]+b[i];
            a[i]=t%10;
            t/=10;
        }
        a[0]=i-1;
        int m=max(a[0],b[0]);
        for(int i=0;i<=m;i++)
        {
            aux=a[i];
            a[i]=b[i];
            b[i]=aux;
        }
    }
    for(int i=b[0];i>=1;i--) printf("%d",b[i]);
    printf("\n");
    return 0;
}