#include <stdio.h>
#include <vector>

using namespace std;

#define MAX_N 256
#define FIN "culori.in"
#define FOUT "culori.out"
#define MOD 9901

int N, C[MAX_N<<1], A[MAX_N<<1][MAX_N];
vector<int> pal[MAX_N<<1];

int main(void)
{
    int i, j;
    vector<int>::iterator it;

    freopen(FIN, "r", stdin);
    freopen(FOUT, "w", stdout);

    scanf("%d", &N);
    for (i = 0; i < 2*N-1; i++) scanf("%d", C+i);

    for (i = 0; i < 2*N-1; i++)
    {
        for (j = 1; i-j >= 0 && i+j < 2*N-1 && C[i-j] == C[i+j]; j++)
            pal[i+j].push_back(2*j);
    }

    A[0][0] = 1;
    for (i = 1; i < 2*N-1; i++)
        for (j = 0; j < N; j++)
        {
            if (j) A[i][j] += A[i-1][j-1];
            for (it = pal[i].begin(); it != pal[i].end(); it++)
            {
                if (j < *it/2) continue;
                A[i][j] += A[i-*it][j-*it/2];
                while (A[i][j] >= MOD) A[i][j] -= MOD;
            }
        }

    printf("%d\n", A[2*N-2][N-1]);

    return 0;
}