#include <bits/stdc++.h>
#define MOD 9901
using namespace std;
ifstream f ("culori.in") ;
ofstream g ("culori.out") ;
int main (){
   int n  , i , k , l ; f >> n ;
    n = 2 * n - 1 ;
    int a [ n + 1 ][ n + 1 ] = {0} ;
    int v [ n + 1 ] ;
   for( i = 1 ; i <= n  ; ++ i )  f >> v [ i ] , a [i ][ i] = 1 ;
   for ( l = 3 ; l <= n ; l+=2 )
    for ( i = 1 ; i + l - 1 <=n ; ++ i ){
        int q = i + l - 1 ;
       if ( v [ i ] == v [ q ] )
       for ( k = i + 1 ; k < q ; k ++ )
       {a [ i ][ q ] += a [ i + 1 ][ k ] * a [ k + 1 ][ q ] ;
       if ( a [ i ][ q ] >= MOD )   a [ i ][ q ] -= MOD ;}}
   g << a [1 ][ n ] ;}