uses math;

var f:array[1..1010]of longint;
    a:array[1..1000]of longint;
    i,n:longint;

function judge(x,y,z:longint):boolean;
begin
 if x>=y then exit(false);
 while z<=n do
  begin
   if x>16 then if x>=y then exit(false)else exit(true);
   x:=x+a[z];if x>21 then exit(true);inc(z);
  end;
end;

function suan(x,y:longint):longint;
begin while (x<16)and(y<n) do begin x:=x+a[y];inc(y);end;exit(y);end;

function g(x:longint):longint;
var turn,now,xx,c1,c2:longint;
begin
 xx:=x;
 if f[x]<>-1 then exit(f[x]);
 if n-x+1<6 then begin f[x]:=0;exit(0);end;
 turn:=1;c1:=a[x]+a[x+2];c2:=a[x+1]+a[x+3];inc(x,4);
 while x<=n do
  begin
   now:=a[x];
   case turn of
    1:begin
       if c1<=16 then
        begin
         inc(c1,now);turn:=1-turn;
         if c1>21 then begin f[xx]:=max(f[xx],g(x+1)+1);break;end;
         inc(x);continue;
        end;
       turn:=1-turn;
      end;
    0:begin
       if judge(c1,c2,x)then
        f[xx]:=max(f[xx],g(suan(c1,x))+1)
         else f[xx]:=max(f[xx],g(suan(c1,x)));
       c2:=c2+now;
       if c2>21 then
        begin f[xx]:=max(f[xx],g(x+1));break;end;
       if (c1>16)and(c2>c1)then
        begin f[xx]:=max(f[xx],g(x+1)+1);break;end;
       if (x=n)and(c2>c1)then f[xx]:=max(f[xx],1);
       turn:=1-turn;inc(x);
      end;
   end;
  end;
 exit(f[xx]);
end;

begin
 assign(input,'jack.in');reset(input);
 assign(output,'jack.out');rewrite(output);
 readln(n);
 for i:=1 to n do read(a[i]);
 fillchar(f,sizeof(f),255);
 writeln(g(1));
 close(output);
end.