var a:array[1..1000] of integer;
i,j,n,k,m,l,aux,nr:longint;
f:text;
ok:boolean;   
procedure citire;
var i:longint;
begin
for i:=1 to n do  
read(f,a[i]);   
end;   
begin
assign(f,'nrtri.in');reset(f);   
readln(f,n);   
nr:=0;   
citire;
close(f);   
repeat
ok:=true;
for i:=1 to n-1 do
    if a[i]>a[i+1] then begin
    ok:=false;
    aux:=a[i];
    a[i]:=a[i+1];
    a[i+1]:=aux;
    end;
    until ok;
assign(f,'nrtri.out');rewrite(f);
for i:=1 to n-2 do  
for j:=i+1 to n-1 do  
for k:=j+1 to n do  
if ((a[k]<=a[j]+a[i]) and (a[j]<=a[i]+a[k]) and (a[k]<=a[i]+a[j])) then inc(nr);   
assign(f,'nrtri.out');rewrite(f);
write(f,nr);
close(f);   
end.