#include <fstream>

using namespace std;

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

const int MOD = 9901;

int n;

int v[520], dp[520][520];

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