#include <bits/stdc++.h>

using namespace std;
int n,v[1005],s,maxx=INT_MIN,min1,min2,k=0,ok=0,kante=-1;

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

void sus(){
f>>n;
for(int i=1;i<=n;i++){
    f>>v[i];

}
sort(v+1,v+n+1);
for(int i=1;i<=n-1;i++){
        maxx=0;
    for(int j=i+1;j<=n;j++){
          for(int d=j+1;d<=n;d++){

            ok=0;
       if(v[i]+v[j]>=v[d]){
        k++;
       }
       else break;

            }


          }
    }
}





int main()
{///suma laturilor mici sa fie mai mare sau egala cu cea mai mare latura for in for in for

sus();
o<<k;
return 0;
}