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

typedef long long int ll;

string arr[20000];

string add(string s1,string s2)
{
    int i,j,k,sum=0,carry=0,len1,len2;
    string ans="";
    if(s1.length()>s2.length())
        swap(s1,s2);
    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)
    {
        ans.push_back(carry + '0');
    }
    reverse(ans.begin(),ans.end());
    return ans;
}

void precal()
{
	int i,j,k;
	arr[0]="0";
	arr[1]="0";
	arr[2]="1";
	arr[3]="1";
	for(i=4;i<10002;i++)
	{
		arr[i]=add((add(arr[i-1],arr[i-2])),arr[i-2]);
	}
}



int main()
{
//    freopen("input.txt","r",stdin);
  //  freopen("output.txt","w",stdout);
    precal();
    int n,i,j;
    while(cin>>n)
    {
    	cout<<arr[n]<<endl;
    }
    return 0;
}