program mark;
type
fxz=array[0..1000] of longint;
var
 f1,f2:text;
 ls,n,m,i,j,ans,x:longint;
 num:fxz;
begin assign(f1,'mark.in');
      assign(f2,'mark.out');
      reset(f1);rewrite(f2);
      readln(f1,n,m);
      for i:=1 to m do
      readln(f1,num[i]);
      readln(f1,x);
      x:=num[x];
      for i:=1 to n-1 do
      for j:=i+1 to n do
      if num[i]>num[j] then begin ls:=num[i];
                                  num[i]:=num[j];
                                  num[j]:=ls;
                             end;
      num[0]:=-1;
      ls:=0;
      for i:=1 to n do begin if num[i]<>num[i-1] then inc(ls);
                             if x=num[i] then break;
                        end;
      m:=n div m;
      ans:=ls div m;
      ls:=ls mod m;
      if ls<>0 then inc(ans);
      writeln(f2,ans);
      close(f1);close(f2);
end.