var f,g:text;
a,b:array[1..1001] of integer;
i,n,c,s,aux,aux1,x,j:integer;
begin
        assign (f,'energii.in');assign(g,'energii.out');
        reset(f);rewrite(g);
        read (f,n,x);
        for i:=1 to n do
                read (f, a[i],b[i]);
        for i:=1 to n-1 do
                for j:=2 to n do
                        if a[i]>a[j] then begin
                                aux:=a[i];aux1:=b[i];
                                a[i]:=a[j];b[i]:=b[j];
                                a[j]:=aux;b[j]:=aux1;end;
        i:=n;
        s:=0; c:=0;
        while (i>0) and (s<x) do begin
              s:=s+a[i];
              c:=c+b[i];
              i:=i-1;end;
        write (g,c);
        close (g);
end.