#include <iostream>
#include <fstream.h>
int main()
{
	int n, v[100], i, k;
	ifstream f("nrtri.in");
	ofstream g("nrtri.out");
	f>>n;
	for (i=1; i<=n; i++)
	{f>>v[i];}
	k=0;
	for (i=1; i<=n; i++)
	{ if (v[i]>0 & v[i+1]>0 & v[i+2]>0)
		{if (v[i]+v[i+1]>v[i+2] & v[i]+v[i+2]>v[i+1] & v[i+1]+v[i+2]>v[i])
		{k++;}
		}
	}
	g<<k;
	f.close();
	g.close();
	return 0;
}