#include <cstdio>
#include <algorithm>
#define LIM 800

using namespace std;

int v[LIM+10];
bool triunghi(int a,int b,int c);
int main()
{
    freopen("nrtri.in","r",stdin);
    freopen("nrtri.out","w",stdout);
    int n,i,j,k,nr=0;
    scanf("%d",&n);
    for(i=1;i<=n;++i)
        scanf("%d",v+i);
    for(i=1;i<=n-2;++i)
        for(j=i+1;j<=n-1;++j)
            for(k=j+1;k<=n;++k)
                if(triunghi(v[i],v[j],v[k]))
                    nr++;
    printf("%d",nr);
    return 0;
}
bool triunghi(int a,int b,int c)
{
    if((a+b>=c)and(a+c>=b)and(b+c>=a))
        return 1;
    return 0;
}