Segment Tree with set on segment and RSQ

uses
    math;

var
    t,sum:array[0..1000000] of int64;
    i,n,m,l,r,x:longint;
    c:char;

procedure upd(v,l,r:longint);
var
    m:longint;
begin
    if t[v] > -1 then
        begin
            t[v + v] := t[v];
            t[v + v + 1]:=t[v];
            m:=(l + r) shr 1;
            sum[v + v]:=t[v] * (m - l + 1);
            sum[v + v + 1]:=t[v] * (r - m);
            t[v]:=-1;
        end;
end;

procedure update(v,l,r,x,y:longint;color:int64);
var
    m:longint;
begin
    if x > y then   exit;
    if (l = x) and (r = y) then
        begin
            t[v] := color;
            sum[v] := color * (r - l + 1);
        end
    else
        begin
            m:=(l + r) shr 1;
            upd(v, l ,r);
            update(v + v, l, m, x, min(m, y), color);
            update(v + v + 1, m + 1, r, max(m + 1, x), y ,color);
            sum[v]:=sum[v + v] + sum[v + v + 1];
        end;
end;

function sum_q(v,l,r,x,y:longint):int64;
var
    m:longint;
begin
    if x > y then   exit(0);
    if (l = x) and (r = y) then
        exit(sum[v])
    else
        begin
            upd(v, l , r);
            m:=(l + r) shr 1;
            exit(sum_q(v + v, l, m, x, min(y, m)) + sum_q(v + v + 1, m + 1, r, max(m + 1,x), y));
        end;
end;

Begin
end.