#include <bits/stdc++.h>

using namespace std;

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

const int NMAX = 256;
const long long MOD = 9901;
long long v[2 * NMAX], dp[2 * NMAX][2 * NMAX];

int main() {
    int n;
    fin>>n;
    for( int i = 1; i <= 2 * n - 1; i ++ )
      fin>>v[i];
    for( int i = 1; i <= 2 * n - 1; i ++ )
      dp[i][i] = 1;
    for( int l = 2; l <= 2 * n - 2; l += 2 ) {
      for( int i = 1; i <= 2*n - 1 - 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][2*n - 1];
    return 0;
}