#include <fstream>
#include <algorithm>
using namespace std;

int v[801];

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

int main(){
    int a,i,x,y,z,k=0;
    fin>>a;
    for(i=1;i<=a;i++){
        fin>>v[i];
    }
    sort(v+1,v+1+a);
    for(i=1;i<=a-2;i++){
        x=v[i];
        y=v[i+1];
        z=v[i+2];
        if(x+y>=z) k++;
    }
    fout<<k;
    return 0;
}