#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 v[2 * NMax - 1][2 * NMax - 1];

int dp(int l, int r){
    if(v[l][r] == -1){
        if(a[l] != a[r]){
            v[l][r] = 0;
            return v[l][r];
        }
        if(l > r){
            v[l][r] = 0;
            return v[l][r];
        }
        if(l == r){
            v[l][r] = 1;
            return v[l][r];
        }
        v[l][r] = 0;

        for(int k = l + 1; k <= r; ++k){
            if(a[l] == a[k]){
                v[l][r] += (dp(l + 1,k - 1) * dp(k,r)) % mod;
            }
        }
        v[l][r] %= mod;
    }
    return v[l][r];
}
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){
        for(int j = 1; j <= n; ++j){
            v[i][j] = -1;
        }
    }

    g << dp(1,n) << '\n';
    return 0;
}