package main

import (
	"fmt"
	"math"
)

func main() {
	var aw, ab, bw, bb, c, d float64
	_, _ = fmt.Scan(&aw, &ab, &bw, &bb, &c, &d)

	// fmt.Println(aw, ab, bw, bb)

	ab, bb = ab-c, bb+math.Min(ab, c)
	if ab < 0 {
		aw, ab, bw = aw+ab, 0, bw-ab
	}
	// fmt.Println(aw, ab, bw, bb)

	bw, aw = bw-d, aw+math.Min(bw, d)
	if bw < 0 {
		bw, bb, ab = 0, bb+bw, ab-bw
	}

	// fmt.Println(aw, ab, bw, bb)
	fmt.Println(aw)
}