#include <bits/stdc++.h>
using namespace std;

int v[802];
int main() {


freopen("nrtri.in", "r", stdin);
freopen("nrtri.out", "w", stdout);

int n;
int i, j, k;
scanf("%d",&n);
for(i = 1; i <= n; i++) {
	scanf("%d", &v[i]);
}

int nr = 0;

for(i = 1; i <= n-2; i++) {
	for(j = i+1; j <= n-1 ; j++) {
		for(k = j+1; k <= n; k++) {

			if ((v[i] + v[j] >= v[k]) && (v[k] + v[j] >= v[i]) && (v[k] + v[i] >= v[j]))
				nr++;
		}
	}
}

printf("%d",nr);



return 0;
}