import java.util.Scanner;


public class Main_yukicoder281 {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        int d = sc.nextInt();
        int[] h = new int[3];
    	for (int i = 0; i < 3; i++) {
    		h[i] = sc.nextInt();
    	}

        int min = Integer.MAX_VALUE;

        if (d == 0) {
        	if (h[1] > h[0] && h[1] > h[2] && h[0] != h[2]) {
        		min = 0;
        	} else if (h[1] < h[0] && h[1] < h[2] && h[0] != h[2]) {
        		min = 0;
        	}
        } else {
        	int[] a = new int[3];
        	int[] tmp = new int[3];
        	for (int i = 0; i < 3; i++) {
        		tmp[i] = h[i];
        	}
        	
        	a[0] = 1;
        	a[1] = 2;
        	a[2] = 0;

        	int tmp2 = getCnt(a, d, tmp);
        	if (tmp2 != -1) {
        		min = Math.min(min, tmp2);
        	}

        	for (int i = 0; i < 3; i++) {
        		tmp[i] = h[i];
        	}
        	a[0] = 1;
        	a[1] = 0;
        	a[2] = 2;

        	tmp2 = getCnt(a, d, tmp);
        	if (tmp2 != -1) {
        		min = Math.min(min, tmp2);
        	}

        	for (int i = 0; i < 3; i++) {
        		tmp[i] = h[i];
        	}
        	a[0] = 0;
        	a[1] = 2;
        	a[2] = 1;

        	tmp2 = getCnt(a, d, tmp);
        	if (tmp2 != -1) {
        		min = Math.min(min, tmp2);
        	}

        	for (int i = 0; i < 3; i++) {
        		tmp[i] = h[i];
        	}
        	a[0] = 2;
        	a[1] = 0;
        	a[2] = 1;

        	tmp2 = getCnt(a, d, tmp);
        	if (tmp2 != -1) {
        		min = Math.min(min, tmp2);
        	}
        }

    	if (min == Integer.MAX_VALUE) {
    		System.out.println("-1");
    	} else {
    		System.out.println(min);
    	}

    	sc.close();
    }
    
    private static int getCnt(int[] a,int d, int[] h) {
    	int tmp = 0;
    	if (h[a[0]] == 0) {
    		return -1;
    	}
    	if (h[a[0]] == h[a[1]]) {
    		h[a[1]] = Math.max(0, h[a[1]] - d);
    		tmp += 1;
    	} else if (h[a[0]] < h[a[1]]) {
    		int tmp2 = (h[a[1]] - h[a[0]] + d) / d;
    		h[a[1]] = Math.max(0, h[a[1]] - tmp2 * d);
    		tmp += tmp2;
    	}
    	if (h[a[1]] == 0) {
    		return -1;
    	}
    	if (h[a[1]] == h[a[2]]) {
    		h[a[2]] = Math.max(0, h[a[2]] - d);
    		tmp += 1;
    	} else if (h[a[1]] < h[a[2]]) {
    		int tmp2 = (h[a[2]] - h[a[1]] + d) / d;
    		h[a[2]] = Math.max(0, h[a[2]] - tmp2 * d);
    		tmp += tmp2;
    	}

    	return tmp;
    }
}