#include <stdio.h>
#define NMAX 801
#define LMAX 30001
 
int N, bat[NMAX], lbat[LMAX], s, last;
int ntri;
 
void search(int p, int q) {
    if (p <= q ) {
        int m = (p+q)/2;
        if (bat[m] <= s) {
            if (last < m)
                last = m; //printf("%d %d\n", m, last);
            search(m+1, q);
        }
        else
            search(p, m-1);
    }
}
int main() {
    FILE *fi = freopen("nrtri.in", "r", stdin);
    FILE *fo = freopen("nrtri.out", "w", stdout);
    int i, j, a;
    scanf("%d", &N);
    for (i = 0; i < N; ++i) {
        scanf("%d", &a);
        ++lbat[a];
    }
    for (i = 1, N = 0; i < LMAX; ++i) {
        for (j = 0; j < lbat[i]; ++j)
            bat[N++] = i;
    }
    for (i = 0; i < N-2; ++i)
        for (j = i+1; j < N-1; ++j) {
            s = bat[i] + bat[j];
            last = -1;
            search(j+1, N-1);
            if (last != -1)
                ntri += last - j;
        }
    //s = 1, last = -1;
    //search(1, 800);
    //printf("%d", last);
    printf("%d\n", ntri);
    return 0;
}