package qunar;

import java.util.Scanner;

public class Main2 {
	static int rel =9999;
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner in = new Scanner(System.in);
		String s;
		while(in.hasNext()){
			s = in.nextLine();
			rel = 9999;
			gs(s);
			if(rel != 9999){
				System.out.println(rel);				
			}else{
				System.out.println("-1");
			}
		}

	}
	public static void gs(String s){
		String[] ar = s.split(" ");
		int n = ar.length;
		int[] arr = new int[n];
		for(int i=0;i<n;i++){
			arr[i] = Integer.valueOf(ar[i]);
		}
		dp(arr,n-2,arr[n-1],0);
		
	}
	public static void dp(int[] arr,int now,int money,int day){
		if(money < 0){
			return;
		}
		if(money == 0){
			if(day < rel){
				rel = day;
				return ;
			}
		}
		if(money%arr[now] == 0){
			if(money/arr[now] < rel){
				rel = money/arr[now]+day;
				return;
			}
		}else{
		for(int i=now;i>=0;i--){
			if(money>=arr[i]){
				dp(arr,i,money-arr[i],day+1);
			}
		}
	}
	}

}