#include <bits/stdc++.h>

using namespace std;
ifstream fin("culori.in");
ofstream fout("culori.out");
const int MODULO = 9901;
int n;
vector<int> ins;
int main()
{
    fin>>n;
    int counter = 0;
    for(int i = 0;i<2*n-1;i++)
    {
        int x;
        fin>>x;
        ins.push_back(x);
    }
    if(n==1)
    {
        fout<<1;
        return 0;
    }
    for(int i = 0;i<2*n-1;i++)
    {
        if(i!=0)
        {
            for(int j = 1;j<=min(2*n-1-i,i);j++)
            {
                if(ins[i-j]==ins[i+j])
                {
                    counter= (counter+1)%MODULO;
                }
                else
                {
                    break;
                }
            }
        }
    }
    fout<<counter<<'\n';
    return 0;
}