#include <bits/stdc++.h>

#define MAXN 260
#define MOD 9901

int N, V[MAXN];
int DP[MAXN][MAXN];

std::ifstream In ("culori.in");
std::ofstream Out("culori.out");

void Citire() {
    In >> N;
    N = 2*N-1;
    for (int i=1; i<=N; ++i)
        In >> V[i];
}

void Rezolvare() {
    for (int i=1; i<=N; ++i)
        DP[i][i] = 1;

    for (int len=2, i, j; len<=N; ++len) {
        for (i=1; i+len-1<=N; ++i) {
            if (V[i] == V[i+len-1]) {
                DP[i][i+len-1] = DP[i+1][i+len-2];
                for (j=i+1; j<i+len-1; ++j)
                    if (V[j] == V[i])
                        DP[i][i+len-1] += DP[i][j] * DP[j][i+len-1],
                        DP[i][i+len-1] %= MOD;
            }
        }
    }   Out << DP[1][N] << '\n';
}

int main()
{
    Citire();
    Rezolvare();

    return 0;
}