#include<fstream>
#define MOD 9901
using namespace std;
ifstream fi("culori.in");
ofstream fo("culori.out");
int n,i,j,k,A[520],Dp[520][520];
int main()
{
    fi>>n;
    for(i=1; i<=2*n-1; i++)
        fi>>A[i];
    for(i=1; i<=2*n-1; i++)
        Dp[i][i]=1;
    for(i=2*n-1; i>=1; i--)
    {
        for(j=i; j<=2*n-1; j+=2)
        {
            if(A[i]==A[j])
            {
                for(k=i+2; k<j; k+=2)
                {
                    if(A[i]==A[k])
                        Dp[i][j]=(Dp[i][j]+((Dp[i+1][k-1]*Dp[k+1][j-1])%MOD))%MOD;
                }
                Dp[i][j]=(Dp[i][j]+Dp[i+1][j-1])%MOD;
            }
        }
    }
    fo<<Dp[1][2*n-1]<<"\n";
    fi.close();
    fo.close();
    return 0;
}