#include <bits/stdc++.h>

using namespace std;

typedef long long LL;

LL f[25][25][25];
LL w(LL a, LL b, LL c)
{
    if (a <= 0 || b <= 0 || c <= 0) return 1;
    if (a > 20 || b > 20 || c > 20) return w(20, 20, 20);
    else if (f[a][b][c] != 0) return f[a][b][c];
    else if (a > 20 || b > 20 || c > 20) f[a][b][c] = w(20, 20, 20);
    else if (a < b && b < c) f[a][b][c] = w(a, b, c - 1) + w(a, b - 1, c - 1) - w(a, b - 1, c);
    else f[a][b][c] = w(a - 1, b, c) + w(a - 1, b - 1, c) + w(a - 1, b, c - 1) - w(a - 1, b - 1, c - 1);
    return f[a][b][c];
}
int main()
{
    LL a, b, c;
    while (cin >> a >> b >> c)
    {
        if (a == -1 && b == -1 && c == -1) return 0;
        printf("w(%lld, %lld, %lld) = %lld\n", a, b, c, w(a, b, c));
    }
}

#include <bits/stdc++.h>

using namespace std;

long long n, f[10000];

int main()
{
    cin >> n;
    for (int i = 1; i <= n; i ++ )
    {
        for (int j = 1; j <= i / 2; j ++ )
            f[i] += f[j];
        f[i] ++ ;
    }
    cout << f[n];

    return 0;
}