#include<bits/stdc++.h>
using namespace std;
ifstream in ("nrtri.in");
ofstream out ("nrtri.out");
int v[1001];
int main()
{
int n,i,cnt=0;
in>>n;
for(i=1;i<=n;i++)
    in>>v[i];
for(i=1;i<=n;i++)
{
    if(v[i]>=v[i+1]+v[i+2])
        cnt++;
}
out<<cnt;
return 0;
}