#include <bits/stdc++.h>

using namespace std;

ifstream fin("culori.in");
ofstream fout("culori.out");

const int NMAX = 256;
const int MOD = 9901;
int v[5 * NMAX], dp[5 * NMAX][5 * NMAX];

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    int n;
    fin>>n;
    n = 2*n - 1;
    for( int i = 1; i <= n; i ++ )
        fin>>v[i], dp[i][i] = 1;

    for( int l = 2; l <= n - 1; l += 2 ) {
        for( int i = 1; i <= n - l; i ++ ) {
            int j = i + l;
            if( v[i] == v[j] ) {
                for( int k = i; k <= j; k ++ ) {
                    if( v[i] == v[k] )
                        dp[i][j] = (dp[i][j] + (dp[i + 1][k - 1] * dp[k][j]) % MOD) % MOD;
                }
            }
        }
    }
    fout<<dp[1][n];
    return 0;
}