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;   
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.