#include <bits/stdc++.h>

using namespace std;
ifstream f("culori.in");
ofstream g("culori.out");

const int NMax = 260;
const int mod = 9901;

int n,x,y,nr;
int a[2 * NMax - 1];
int dp[2 * NMax - 1][2 * NMax - 1];

int main()
{
    f >> n;
    n = n * 2 - 1;
    for(int i = 1; i <= n; ++i)
        f >> a[i];
    for(int i = 1; i <= n; ++i)
        dp[i][i] = 1;

    for(int len = 3; len <= n; len += 2){
        for(int l = 1; l <= n; ++l){
            int r = l + len - 1;

            if(r > n)
                continue;
            if(a[l] != a[r])
                continue;

            int ans = 0;
            for(int k = l + 1; k <= r; ++k){
                if(a[l] == a[k])
                    ans += (dp[l + 1][k - 1] * dp[k][r]) % mod;
            }
            dp[l][r] = ans % mod;
        }
    }

    g << dp[1][n] << '\n';
    return 0;
}