#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#define ll long long
#define mst(a,x) memset(a,x,sizeof(a))
using namespace std;

const int N = 60;
ll dp[N + 5][N + 5], ans[N + 5];
int main()
{
    mst(dp, 0);
    for(int i = 0; i <= N; i++) dp[i][0] = 1;
    mst(ans, 0);
    for(int i = 1; i <= N; i++)
    {
        ans[i] = 0;
        for(int j = 1; j <= N; j++)
        {
            dp[i][j] = dp[i - 1][j];
            if(i >= 3) dp[i][j] += dp[i - 3][j - 1];
            else 
            {
                if(j == 1) dp[i][j]++;
            }
            ans[i] += dp[i][j];
        }
    }
    int n;

    while(~scanf("%d", &n)) printf("%lld\n", ans[n]);
    
    return 0;
}