#include <fstream>
#include <algorithm>

using namespace std;

ifstream in("nrtri.in");
ofstream out("nrtri.out");

int l[803], n, poate;
int main()
{
    in >> n;
    for(int i = 1; i <= n; i++) in >> l[i];

    sort(l+1, l+n+1);

    for(int i = 1; i <= n-2; i++) {
        if(l[i]+l[i+1] >= l[i+2]) poate++;
    }

    out << poate;
    return 0;
}