#include <stdio.h>

const int MAXN = 256*2 + 1;
const int MOD = 9901;

int d[MAXN];
int a[MAXN][MAXN];

int main()
{
    FILE *f;
    int n,i,j,k;

    f = fopen("culori.in","r");
    fscanf(f,"%d",&n);
    n = n*2 - 1;
    for (i = 1; i <= n; i++)
    {
        fscanf(f,"%d",&d[i]);
        a[i][i] = 1;
    }
    fclose(f);

    for (i = n-2; i >= 1; i--)
    {
        for (j = i; j <= n; j+=2)
        {
            if (d[i] == d[j])
            {
                for (k = i+1; k < j; k+=2)
                    if (d[i+1] == d[k])
                    {
                        a[i][j] += a[i+1][k]*a[k+1][j];
                        a[i][j] %= MOD;
                    }
            }
        }
    }

    f = fopen("culori.out","w");
    fprintf(f,"%d",a[1][n]);
    fclose(f);
    
    return 0;
}