#include <iostream>
#include <fstream>
#define Nmax 260
#define MOD 9901

using namespace std;

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

int n;
int dp[2*Nmax][2*Nmax], v[2*Nmax];

int main()
{
    f >> n;
    n = 2*n-1;
    for (int i = 1; i <= n; i++)
    {
        f >> v[i];
        dp[i][i] = 1;
    }
    for (int l = 1; l <= n; l++)
    {
        for (int i = 1; i+l-1 <= n; i++)
        {
            int j=i+l-1;
            if (v[i] != v[j]) continue;

            for (int k = i + 1; k < j; k++)
            {
                if(v[i+1] == v[k])
                    dp[i][j]=(dp[i][j] + dp[i+1][k]*dp[k+1][j])%MOD;
            }
        }
    }
    g << dp[1][n];
    return 0;
}