
#include <bits/stdc++.h>
using namespace std;
const int MAXN = 33000;
long long dp[MAXN] = {0};
int main () {
dp[0] = 1;
for (int i = 1; i <= 3; i++) {
for (int j = i; j < MAXN; j++) {
dp[j] += dp[j-i];
}
}
int n;
while(~scanf("%d", &n)){
printf("%I64d
", dp[n]);
}
return 0;
}