#include<fstream.h>
long n,x[100005];
int main()
{ifstream fin("numarare.in");
  fin>>n;
  long k,j,i,sw,nr=n-1;
   for(i=1;i<=n;++i)
	   fin>>x[i];
 fin.close();
 ofstream fout("numarare.out");
  for(i=1;i<=n;++i)
	 for(j=i+3;j<=n;j+=2)
	  {sw=1; 
	    for(k=1;k<=(j-i)/2;++k)
		  if(x[i+k]+x[j-k]!=x[j]+x[i])
		  {sw=0;
		   break;
		  }
		if(sw)
		 {//fout<<i<<" "<<j<<"\n";
			 ++nr;
		 }
	  }
 fout<<nr;
 fout.close();
 return 0;
}