type aaa=array[1..20] of boolean;
var
 i,j,m,n,k,ans:longint;
 o0:aaa;
 h:array[1..500] of longint;
procedure dfs(v,s:longint;o:aaa);
var i:longint; o1:aaa;
begin
 if s=k then begin inc(ans); exit;end;
 if v>n then exit;
 fillchar(o1,sizeof(o1),0);
 for i:=1 to h[v] do o1[i]:=o[i];
 dfs(v+1,s,o1);
 for i:=1 to  h[v] do
  begin
  if not o1[i] then
   begin
    o1[i]:=true;
    dfs(v+1,s+1,o1);
    o1[i]:=false;
   end;
  end;
end;
begin
 assign(input,'boarda.in');reset(input);
 assign(output,'boarda.txt');rewrite(output);
 readln(n,k);
 for i:=1 to n do read(h[i]);
 readln;
 dfs(1,0,o0);
 writeln(ans);
 close(input);close(output);
end.