#include <iostream>
#include <fstream>

using namespace std;

ifstream f ("culori.in");
ofstream g ("culori.out");

const int NMAX = 256 + 1;
const int MOD = 9901;

int n;
int culoare[2 * NMAX - 1];
int dp[2 * NMAX - 1][2 * NMAX - 1];

void citeste() {
    f >> n;
    n = 2 * n - 1;
    for (int i = 1; i <= n; i++) f >> culoare[i], dp[i][i]++;
}

int rezolva() {
    if (culoare[1] != culoare[n]) return 0;

    for (int lg = 3; lg <= n; lg += 2) {
        for (int i = 1; i + lg - 1 <= n; i++) {
            int j = i + lg - 1;
            if (culoare[i] == culoare[j]) {
                for (int k = i + 1; k < j; k++)
                    dp[i][j] = (dp[i][j] + dp[i + 1][k] * dp[k + 1][j]) % MOD;
            }
        }
    }
    return dp[1][n];
}

int main() {
    citeste();
    g << rezolva();
    return 0;
}