#include <cstdio>
#include <algorithm>
#define NMAX 805
using namespace std;

FILE *f = freopen("nrtri.in", "r", stdin);
FILE *g = freopen("nrtri.out", "w", stdout);
int v[NMAX], n;
int nr = 0;
void read() {
    scanf("%d", &n);
    for(int i = 1; i<=n; i++)
        scanf("%d", &v[i]);
}
void solve() {
    sort(v + 1, v + n + 1);
    for(int i = 1; i<n - 1; i++)
        for(int j = i + 1; j<n; j++)
        for(int k = j + 1; k <= n; k ++) {
            int triangle = 1;
            if(v[i] + v[j] < v[k])
            {
                triangle = 0; break;
            }
            if(v[i] + v[k] < v[j])
            triangle = 0;
            if(v[j] + v[k] < v[i])
            triangle = 0;
            if(triangle)
            nr ++;
        }

}
int main(){
    read();
    solve();
    printf("%d", nr);
    return 0;
}