#include <stdio.h>
#include <stdlib.h>
int main()
{
    FILE *fin = fopen("nrtri.in", "r");
    FILE *fout = fopen("nrtri.out", "w");

    int n;
    int v[800];
    int count = 0;
    fscanf(fin, "%d", &n);
    for (int i = 0; i < n; i++) {
		fscanf(fin, "%d", &v[i]);
		//printf("%d ", v[i]);
    }
    for (int st = 0; st < n-2; st++) {
		//printf("\n%d ", st);
		for (int mij = st + 1; mij < n-1; mij++) {
			//printf("%d ", st);
			for (int dr = mij + 1; dr < n; dr++) {
				//printf("%d ", dr);
				if (v[st] + v[mij] >= v[dr] && v[mij] + v[dr] >= v[st] && v[st] + v[dr] >= v[mij]) {
					count += 1;
				}
			}
		}
    }

    //printf("%d", count);

    fprintf(fout, "%d", count);
    return 0;
}