Dp 神奇的状态转移……

Program fd;
const
   mo=1000000007;
var
   n,i,j:longint;
   c,tot:array[1..15] of longint;
   f:array[0..15,0..15,0..15,0..15,0..15,0..15] of int64;
function dfs(a1,a2,a3,a4,a5,last:longint):int64;
var
   i,j:longint;
   ans,q:int64;
   a:array[1..5] of longint;
begin
   if f[a1,a2,a3,a4,a5,last]>0 then exit(f[a1,a2,a3,a4,a5,last]);
   a[1]:=a1;a[2]:=a2;a[3]:=a3;a[4]:=a4;a[5]:=a5;
   ans:=0;
   for i:=1 to 5 do
      if (a[i]>0) then
      begin
         if (last=i+1) and (a[i]=1) then continue;

  //     if (last=i+1) then dec(a[i]);
         dec(a[i]);
         if i>1 then inc(a[i-1]);


         q:=dfs(a[1],a[2],a[3],a[4],a[5],i);
         inc(a[i]);
         if i>1 then dec(a[i-1]);

         if last=i+1 then ans:=(ans+(a[i]-1)*q) mod mo
         else ans:=(ans+a[i]*q) mod mo;


  //     if (last=i+1) then inc(a[i]);
      end;
   f[a1,a2,a3,a4,a5,last]:=ans;
   exit(ans);
end;
begin
   read(n);
   fillchar(tot,sizeof(tot),0);
   for i:=1 to n do
   begin
      read(c[i]);
      inc(tot[c[i]]);
   end;
   fillchar(f,sizeof(f),0);
   for i:=1 to n do f[0,0,0,0,0,i]:=1;
   writeln(dfs(tot[1],tot[2],tot[3],tot[4],tot[5],0));



end.