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

using namespace std;

int n;
int a[2*NMax-1];
int dp[2*NMax-1][2*NMax-1];

void Read()
{
    ifstream f ("culori.in");
    f>>n;
    n = n+n-1;
    int i;
    for (i=1; i<=n; ++i)
        f>>a[i];
    f.close();
}

void Solve()
{
    int i, d, k, j;
    for (i=1; i<=n; ++i)
        dp[i][i] = 1;
    for (d = 3; d<=n; d+=2)
    {
        for (i=1, j=d; j<=n; ++i, ++j)
        {
            if (a[i] == a[j])
                for (k=i+1; k<j; ++k)
                {
                    if (((k-(i+1)-1)&1) && a[i+1] == a[k] && a[i] == a[k+1])
                    {
                    // && a[k+1] == a[j] dar a[i] == a[j] si a[i] == a[k+1] deci nu mai are rost
                        dp[i][j] += dp[i+1][k]*dp[k+1][j];
                        dp[i][j] %= MOD;
                    }
                }
        }
    }
}

void Write()
{
    ofstream g("culori.out");
    g<<dp[1][n]<<"\n";
    g.close();
}

int main()
{
    Read();
    Solve();
    Write();
    return 0;
}