#include <bits/stdc++.h>
#define DM 805
using namespace std;
ifstream fin("nrtri.in");
ofstream fout("nrtri.out");
int v[DM],n,ans;
int main()
{
    fin>>n;
    for(int i=1;i<=n;++i) fin>>v[i];
    sort(v+1,v+n+1);
    for(int i=1;i<=n;++i) for(int j=i+1;j<=n;++j)
        for(int k=j+1;v[k]<=v[i]+v[j] && k<=n;++k) ans++;
    fout<<ans;
    return 0;
}