#include <stdio.h>
const int mod=9901;
int c[257],a[700][700],i,j,k,n;
int main(void)
{
    freopen("culori.in","r",stdin);
    freopen("culori.out","w",stdout);
    scanf("%d",&n);
    n=2*n-1;
    for (i=1;i<=n;i++)
    {
        scanf("%d",&c[i]);
        a[i][i]=1;
    }
    int p;
    for (p=1;p<=n;p++)
        for (i=1;i+p-1<=n;i++)
        {
            j=i+p-1;
            if (c[i]==c[j])
            {
                for (k=i+1;k<=j;k++)
                    a[i][j]=(a[i][j]+a[i+1][k-1]*a[k][j])%mod;
            }
        }
    printf("%d\n",a[1][n]);
    return 0;
}