int dp[N][2];

int main()
{
    //freopen("in.txt", "r", stdin);
    //freopen("library.in", "r", stdin);
    //freopen("library.out", "w", stdout);
    int n, a, b;
    cin >> n >> a >> b;
    dp[0][0] = 1;
    dp[0][1] = 1;
    for (int i = 0; i < n; ++i) {
        for (int j = 1; j <= a && i + j <= n; ++j)
            dp[i + j][0] = (dp[i + j][0] + dp[i][1]) % MOD;
        for (int j = 1; j <= b && i + j <= n; ++j)
            dp[i + j][1] = (dp[i + j][1] + dp[i][0]) % MOD;
    }
    cout << (dp[n][0] + dp[n][1]) % MOD << endl;
    return 0;
}