program pairs;
type vector=array[1..100000] of 0..1;
var v:array[1..100000] of int64;
    r,n,x,a,b:int64;
    i,j:longint;
    f,g:text;
    ciur:vector;
begin
     assign(f,'pairs.in');
     assign(g,'pairs.out');
     rewrite(g);
     reset(f);
     read(f,n);

     for i:= 1 to n do
         read(f,v[i]);
     x:=0;


     for i:=1 to n do
           ciur[i]:=1;
     for i:=2 to n div 2 do
       for j:=2 to n div i do
            ciur[i*j]:=0;


     for i:=1 to n do
       for j:=i+1 to n do
       begin
                begin
                     a:=v[i];
                     b:=v[j];
                     if (a  mod 2=0) and (b mod 2=0) then x:=x
                     else
                         if (ciur[a]=1) and (ciur[b]=1) then inc(x)
                        { else
                         begin
                              repeat
                                    r:=a mod b;
                                    a:=b;
                                    b:=r;
                              until r=0;
                         if a=1 then inc(x);
                         end;}
                end;
       end;
     write(g,x);

     close(f);
     close(g);
end.