type gener=record
           e,c:longint;
     end;

var f1,f2:text;
    eng,cost,i,j,g,w:longint;
    a:array[1..1010] of gener;
    aux:gener;
begin
        assign(f1,'energii.in');
        reset(f1);
        assign(f2,'energii.out');
        rewrite(f2);
        read(f1,g,w);
        for i:=1 to g do
        begin
                read(f1,a[i].e,a[i].c);
                eng:=eng+a[i].e;
                cost:=cost+a[i].c;
        end;
        for i:=1 to g-1 do
                for j:=i+1 to g do
                        if a[i].c<a[j].c then
                        begin
                                aux:=a[i];
                                a[i]:=a[j];
                                a[j]:=aux;
                        end
                        else if (a[i].c=a[j].c)and(a[i].e<a[j].e) then
                        begin
                                aux:=a[i];
                                a[i]:=a[j];
                                a[j]:=aux;
                        end;
        for i:=1 to g do
                if eng-a[i].e>=w then
                begin
                        eng:=eng-a[i].e;
                        cost:=cost-a[i].c;
                end;
        writeln(f2,cost);
        close(f1);
        close(f2);
end.