#include<bits/stdc++.h>
#define MOD 9901
using namespace std;
ifstream f("culori.in");
ofstream g("culori.out");
int n,v[285],dp[285*2][285*2];
long long cnt;
int main()
{
    f>>n;
    n=n*2-1;
    for(int i=1;i<=n;++i)
        {
            f>>v[i];
            dp[i][i]=1;
        }
    for(int ii=2;ii<=n;ii+=2)
        for(int i=1;i<=n-2;++i)
    {
        int j=i+ii;
        if(v[i]==v[j] && (i+j)%2==0)
           {
               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)%MOD;
           }
    }

    g<<dp[1][n]%MOD;
}