#include <fstream>

using namespace std;

ifstream cin("culori.in");
ofstream cout("culori.out");

const int MAXN = 260;
const int mod = 9901;

int n, m;
int c[2 * MAXN];
int dp[2 * MAXN][2 * MAXN];

void read()
{
    cin >> n;
    m = 2 * n - 1;
    for (int i = 1; i <= m; i++)
        cin >> c[i];
}

void make_dp()
{
    for (int i = 1; i <= m; i++)
        dp[i][i] = 1;
    for (int len = 1; len < m; len++)
    {
        for (int i = 1; i + len <= m; i++)
        {
            int j = i + len;
            if (c[i] != c[j]) continue;
            for (int k = i + 1; k < j; k++)
                dp[i][j] = (dp[i][j] + (dp[i + 1][k] * dp[k + 1][j])) % mod;
        }
    }
}

void afis()
{
    cout << dp[1][m];
}

int main()
{
    read();
    make_dp();
    afis();
    return 0;
}