program happya;
var
  n,m,i,j,ans:longint;
  cha:char;
  candy:array[1..100000] of longint;
procedure add;
var
  a,b,c:longint;
  begin
    readln(a,b,c);
    for i:=a to b do
      candy[i]:=candy[i]+c;
  end;
procedure put;
var
  a,b,p,max:longint;
  begin
    max:=-1;
    readln(a,b);
    for i:=a to b do
      if candy[i]>max then
        begin
          max:=candy[i];
          p:=i;
        end;
    writeln(max);
    candy[p]:=0;
  end;
begin
  assign(input,'happya.in');
  assign(output,'happya.out');
  reset(input);
  rewrite(output);
  readln(n,m);
  for j:=1 to m do
    begin
      read(cha);
      if cha='I' then add
                 else put;
    end;
  close(input);
  close(output);
end.