#include<fstream>
#include<algorithm>
using namespace std;
int main(){
    ifstream in("nrtri.in");
    ofstream out("nrtri.out");
    long long int v[800],n,l=0;
    in>>n;
    for(int i=0;i<n;i++){
        in>>v[i];
    }
    sort(v,v+n);
    for(long long int i=0;i<n-2;i++){
        if(v[i]+v[i+1]>=v[i+2]){
            l++;
        }
    }
    out<<l;
}