program writing;
var
  len1,len2:longint;
  s1,s2:ansistring;
  suma,nowa:array['a'..'z'] of longint;
  sumb,nowb:array['A'..'Z'] of longint;
procedure main;
var
  i,flag,ans:longint;
begin
  fillchar(suma,sizeof(suma),0);
  fillchar(sumb,sizeof(sumb),0);
  fillchar(nowa,sizeof(nowa),0);
  fillchar(nowb,sizeof(nowb),0);
  for i:=1 to len1 do
    if s1[i] in ['a'..'z'] then
      inc(suma[s1[i]])
    else
      inc(sumb[s1[i]]);
  flag:=0;
  ans:=0;
  for i:=1 to len2 do
  begin
    if s2[i] in ['a'..'z'] then begin
      inc(nowa[s2[i]]);
      if nowa[s2[i]]>suma[s2[i]] then inc(flag);
    end
    else begin
      inc(nowb[s2[i]]);
      if nowb[s2[i]]>sumb[s2[i]] then inc(flag);
    end;
   if i>=len1 then
   begin
     if flag=0 then inc(ans);
     if s2[i-len1+1] in ['a'..'z'] then begin
       if nowa[s2[i-len1+1]]>suma[s2[i-len1+1]] then dec(flag);
       dec(nowa[s2[i-len1+1]]);
     end
     else begin
       if nowb[s2[i-len1+1]]>sumb[s2[i-len1+1]] then dec(flag);
       dec(nowb[s2[i-len1+1]]);
     end;
   end;
 end;
 writeln(ans);
end;
begin
  assign(input,'writing.in');
  assign(output,'writing.out');
  reset(input);
  rewrite(output);
  readln(len1,len2);
  readln(s1);
  readln(s2);
  main;
  close(input);
  close(output);
end.