program ex(f1,f2);
 type
  zn=array [1..100] of longint;
  ka=array [0..1000] of longint;
 var
  a:zn;
  c:ka;
  f1,f2:text;
  i,j,k,m,ans,n,p,l,step:longint;
 procedure dfs(step:longint);
  var
   i,j,p:longint;
  begin
   for i:=1 to k do
     if (c[step-1]<>i)and(a[i]>0) then
      begin
       a[i]:=a[i]-1;
       c[step]:=i;
       if step<n then dfs(step+1) else ans:=(ans+1) mod 1000000007;
       a[i]:=a[i]+1;
      end;
  end;


 begin
  assign(f1,'color.in'); reset(f1);
  assign(f2,'color.out'); rewrite(f2);
  readln(f1,k);
  for i:=1 to k do read(f1,a[i]);
  n:=0;
  for i:=1 to k do n:=n+a[i];
  ans:=0;
  c[0]:=0;
  dfs(1);
  writeln(f2,ans);
  close(f1);
  close(f2);
 end.