using namespace std;
#include<iostream>
#include<fstream>
#include<cstdio>
int a[100001],N;
int b[1000][1000];
ofstream fout("numarare.out");
void solve()
{int i,j;
    for(i=1;i<=N-1;i++)
      b[i][i+1]=1;
    for(i=3;i<=N;i+=2)
     for(j=1;j<=N;j++)
       b[j][j+i]=(a[j]+a[j+i]==a[j+1]+a[j+i-1])?1+b[j+1][j+i-1]+b[j][j+1]+b[j+i-1][j+i]:b[j+1][j+i-1]+b[j][j+1]+b[j+i-1][j+i];
    fout<<b[1][N];
}
void cit()
{int i;
    ifstream fin("numarare.in");
    fin>>N;
    for(i=1;i<=N;i++)
     fin>>a[i];
   fin.close();
}
int main()
{
    cit();
    solve();
    fout.close();
    return 0;


}