#include<bits/stdc++.h>
using namespace std;

string fib[20000];

string addition(string s1,string s2)
{
	if(s1.length()>s2.length())
		swap(s1,s2);
	int i,j,k,len1,len2,carry=0,sum=0;
    string ans="";
    reverse(s1.begin(),s1.end());
    reverse(s2.begin(),s2.end());
    len1=s1.length();
    len2=s2.length();
    for(i=0;i<len1;i++)
    {
    	sum=(s1[i]-'0'+s2[i]-'0')+carry;
    	ans.push_back(sum%10+'0');
    	carry=sum/10;
    }
    for(i=len1;i<len2;i++)
    {
    	sum=(s2[i]-'0')+carry;
    	ans.push_back(sum%10+'0');
    	carry=sum/10;
    }
    if(carry!=0)
    {
    	ans.push_back(carry+'0');
    }
    reverse(ans.begin(),ans.end());


    return ans;
}

string fibo(int n)
{
	if(n==1 || n==2)
		return "1";
       if(fib[n]!="")
            return fib[n];
	return fib[n]=addition(fibo(n-1),fibo(n-2));
}


int main()
{
//	freopen("in.txt","r",stdin);
//	freopen("out.txt","w",stdout);
	int n;
	while(cin>>n && n)
	{
        cout<<fibo(n*2)<<endl;
	}
	return 0;
}