package main

import (
	"fmt"
)

func minInt(a, b int) int {
	if a < b {
		return a
	}
	return b
}

func resolve(Aw, Ab, Bw, Bb, C, D int) int {
	if Ab < C {
		Aw -= C - Ab
		Bw += C - Ab
	}
	return Aw + minInt(Bw, D)
}

func main() {
	var Aw, Ab, Bw, Bb, C, D int
	fmt.Scanf("%d %d\n", &Aw, &Ab)
	fmt.Scanf("%d %d\n", &Bw, &Bb)
	fmt.Scanf("%d %d\n", &C, &D)
	fmt.Println(resolve(Aw, Ab, Bw, Bb, C, D))
}