import java.io.InputStream;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.BitSet;
import java.util.Comparator;
import java.util.Deque;
import java.util.HashMap;
import java.util.HashSet;
import java.util.InputMismatchException;
import java.util.Map;
import java.util.PriorityQueue;
import java.math.BigDecimal;
import java.math.BigInteger;
    
public class Main{
 
static final InputStream in=System.in;
static final PrintWriter out=new PrintWriter(System.out);
static final int INF=Integer.MAX_VALUE;
static final long LINF=Long.MAX_VALUE/2;
static int d;
static int[] h;
 
public static void main(String[] args) throws IOException{
InputReader ir=new InputReader(in);
d=ir.nextInt();
h=ir.nextIntArray(3);
out.println(dfs(0));
out.flush();
}

public static int dfs(int dep){
 if(check()) return dep;
 if((h[0]==0&&h[1]==0)||(h[1]==0&&h[2]==0)||(h[2]==0&&h[0]==0)) return -1;
 int temp;
 int[] res=new int[3];
 for(int i=0;i<3;i++){
  if(h[i]!=0){
   temp=h[i];
   h[i]=Math.max(0,h[i]-d);
   res[i]=dfs(dep+1);
   h[i]=temp;
  }
 }
 int min=INF;
 for(int i=0;i<3;i++){
  if(res[i]>0) min=Math.min(res[i],min);
 }
 return (min==INF)?-1:min;
}

public static boolean check(){
 if(h[0]!=h[1]&&h[1]!=h[2]&&h[2]!=h[0]&&((h[1]>h[0]&&h[1]>h[2])||(h[1]<h[0]&&h[1]<h[2]))) return true;
 else return false;
}

static class InputReader {
private InputStream in;
private byte[] buffer=new byte[1024];
private int curbuf;
private int lenbuf;
 
public InputReader(InputStream in) {this.in=in;}
  
public int readByte() {
if(lenbuf==-1) throw new InputMismatchException();
if(curbuf>=lenbuf){
curbuf= 0;
try{
lenbuf=in.read(buffer);
}
catch (IOException e) {
throw new InputMismatchException();
}
if(lenbuf<=0)
return -1;
}
return buffer[curbuf++];
}
 
public boolean isSpaceChar(int c){return !(c>=33&&c<=126);}
 
private int skip() {int b; while((b = readByte())!=-1&&isSpaceChar(b)); return b;}
 
public String next() {
int b=skip();
StringBuilder sb=new StringBuilder();
while(!isSpaceChar(b)){
sb.appendCodePoint(b);
b=readByte();
}
return sb.toString();
}
 
public int nextInt() {
int c=readByte();
while (isSpaceChar(c)) c=readByte();
boolean minus=false;
if (c=='-') {
minus=true;
c=readByte();
}
int res=0;
do{
if(c<'0'||c>'9') throw new InputMismatchException();
res=res*10+c-'0';
c=readByte();
}while(!isSpaceChar(c));
return (minus)?-res:res;
}
 
public long nextLong() {
int c=readByte();
while (isSpaceChar(c)) c=readByte();
boolean minus=false;
if (c=='-') {
minus=true;
c=readByte();
}
long res = 0;
do{
if(c<'0'||c>'9') throw new InputMismatchException();
res=res*10+c-'0';
c=readByte();
}while(!isSpaceChar(c));
return (minus)?-res:res;
}
 
public double nextDouble(){return Double.parseDouble(next());}
 
public BigInteger nextBigInteger(){return new BigInteger(next());}
 
public int[] nextIntArray(int n){
int[] a=new int[n];
for(int i=0;i<n;i++) a[i]=nextInt();
return a;
}
 
public char[][] nextCharMap(int n,int m){
char[][] map=new char[n][m];
for(int i=0;i<n;i++) map[i]=next().toCharArray();
return map;
}
}
}