#include<stdio.h>
#define N 256
#define MOD 9901
int v[N*2][N*2];
int cul[N*2];
int main(){
    FILE *fin,*fout;
    fin=fopen("culori.in","r");
    fout=fopen("culori.out","w");
    int n;
    fscanf(fin,"%d",&n);
    n=n*2-1;
    int i;
    for(i=0;i<n;i++)
        fscanf(fin,"%d",&cul[i]);
    for(i=n-1;i>=0;i--){
        v[i][i]++;
        int k;
        for(k=i+1;k<n;k++)
            if((i+k)%2==0&&cul[i]==cul[k]){
                int j;
                for(j=i+1;j<k;j++)
                    v[i][k]=(v[i][k]+v[i+1][j]*v[j+1][k])%MOD;
            }
    }
    fprintf(fout,"%d",v[0][n-1]);
    return 0;
}