print((function (f, g, a, b, x, y)
	return f(g(a,b,x,y))
end)(function (n)
	return (n==math.floor(n) and "%.0f" or "%.12f"):format(n)
end, function (a, b, x, y)
	a,b,x,y = tonumber(a),tonumber(b),tonumber(x),tonumber(y)
	if a>b then return x*b/a<y and x+x*b/a or y+y*a/b end
	if a<b then return y*a/b<x and y+y*a/b or x+x*b/a end
	return math.min(x,y)*2
end, io.stdin:read("*l"):match("(%d+)%s(%d+)%s(%d+)%s(%d+)")))