#include <fstream>
#include <algorithm>

using namespace std;

ifstream cin("culori.in");
ofstream cout("culori.out");

const int LIM=512, MOD=9901;
int n, v[LIM], dp[LIM][LIM];
int main()
{
    cin>>n;
    n=2*n-1;
    for(int i=1; i<=n; ++i)
        cin>>v[i];
    for(int i=1; i<=n; ++i)
        dp[i][i]=1;
    for(int lg=3; lg<=n; lg+=2)
        for(int i=1; i<=n-lg+1; ++i)
        {
            int j=i+lg-1;
            if(v[i]==v[j])
                for(int k=i+1; k<j; k+=2)
                    if(v[i]==v[k+1])
                        dp[i][j]+=dp[i+1][k]*dp[k+1][j]%MOD;
        }
    cout<<dp[1][n];
    return 0;
}