#include <iostream>
#include <algorithm>

using namespace std;
const int NMAX=800;
const int LOGMAX=9;

int a[NMAX+1];

int main()
{
    int n;
    cin>>n;
    for(int i=1;i<=n;i++)
    {
        cin>>a[i];
    }
    sort(a+1,a+1+n);
    int ans=0;
    for(int i=1;i<=n;i++)
    {
        for(int j=1;j<=n;j++)
        {
            if(i==j)
                continue;
            //cautarea binara
            int low=max(a[i],a[j])-min(a[i],a[j]);//lower bound
            int high=a[i]+a[j];//upper bound

            int indexLow=0;
            for(int bit=LOGMAX;bit>=0;bit--)
            {
                indexLow+=(1<<bit);
                if(indexLow>n || a[indexLow]>=low)
                    indexLow-=(1<<bit);
            }
            indexLow++;

            int indexHigh=0;
            for(int bit=LOGMAX; bit>=0;bit--)
            {
                indexHigh+=(1<<bit);
                if(indexHigh>n || a[indexHigh]>high)
                    indexHigh-=(1<<bit);
            }
            //[indexLow,indexHigh]
            int total = indexHigh-indexLow;
            if(indexLow<=i && i<=indexHigh)
                total--;
            if(indexLow<=j && j<=indexHigh)
                total--;
            ans+=total;
        }
    }
    cout<<ans<<'\n';
}