const
 inf=1000000007;
var
 tot,n,i,j,k,ans:longint;
 h,a,d:array[1..502]of longint;
 v:array[1..502,1..502]of boolean;
 f:array[1..502]of boolean;

 function zhan(x:longint):boolean;
  var i:longint;
  begin
   for i:=x to k do
    if d[a[i]]=0 then exit(true);
   exit(false);
  end;

 procedure make(x,now:longint);
  var i,j,m,ii:longint;
  begin
   if x=k then begin ans:=(ans+now)mod inf;exit;end;
   if zhan(x+1)then exit;

   x:=x+1;
   for i:=1 to h[a[x]] do
    if v[a[x],i] then
     begin
       m:=n;
       v[a[x],i]:=false;dec(d[a[x]]);
       for j:=a[x]+1 to n do
        begin
         if h[j]<i then begin m:=j-1;break;end;
         if f[j] then begin v[j,i]:=false;dec(d[j]);end;
                        //if d[j]<1 then exit;end;
        end;
       make(x,now);
       for j:=m downto a[x] do
        if f[j] then begin v[j,i]:=true;inc(d[j]);end;
     end;
  end;

 procedure dfs(dn,x:longint);
  var i:longint;
  begin
   if dn=k then
    begin
     a[k]:=x;f[x]:=true;
     fillchar(v,sizeof(v),true);
     d:=h;
     make(0,1);exit;
    end;

   a[dn]:=x;f[x]:=true;
   for i:=x+1 to n-k+dn+1 do dfs(dn+1,i);
   f[x]:=false;
  end;

begin
assign(input,'boarda.in');reset(input);
assign(output,'boarda.out');rewrite(output);
 readln(n,k);
 for i:=1to n do read(h[i]);

 ans:=0;
 for i:=1 to n+1-k do
  begin
   fillchar(f,sizeof(f),0);
   dfs(1,i);
  end;
 writeln(ans);
close(input);close(output);
end.