program cojs_p486;
var
	l,i,j,c0,c1,m0,m1,l0,l1:longint;
procedure ass;
begin
	assign(input,'bs.in');
	assign(output,'bs.out');
	reset(input);
	rewrite(output);
end;
procedure cls;
begin
	close(input);
	close(output);
end;
procedure swap(var a,b:longint);
var
	t:longint;
begin
	t:=a;
	a:=b;
	b:=t;
end;
begin
	ass;
	while not(eof) do
	begin
		readln(c0,c1,m0,m1);
		if m0<>0 then
		l0:=c0 div m0;
		if m1<>0 then
		l1:=c1 div m1;
		if l0>l1
			then begin swap(c0,c1); swap(m0,m1); swap(l0,l1); end;
		if (m0=0) and (m1<>0)
		then begin l:=m1; writeln(l); end;
		if (m1=0) and (m0<>0)
		then begin l:=m0; writeln(l); end;
                if (m1=0) and (m0=0)
                then writeln('0');
		if (m1<>0) and (m0<>0)
		then begin l:=c0+(l0+1)*m1; writeln(l); end;
	end;
	cls;
end.