#include <cstdio>
#include <cstring>
#include <climits>
#include <algorithm>
using namespace std;

//namaega184
int f(int a){printf("%d\n",a);}
int main(){
	int d;int h[3];scanf("%d",&d);for(int i=0;i<3;i++)scanf("%d",&h[i]);
	int ans=1000000000,inf=1000000000;
	auto nextpos=[&](int now,int next){return (now-(next-1)+d-1)/d;};
	int h1=h[0],h2=h[2],m,a=0;
	if(d>0){if(h1>=h[1]){m=nextpos(h1,h[1]);h1=max(0,h1-d*m),a+=m;}
	if(h[1]<=h2){m=nextpos(h2,h[1]);h2=max(0,h2-d*m);a+=m;}
	if(h1==h2){m=nextpos(h1,h2);h1=max(0,h1-d*m);a+=m;}
	}
	if(h1>=0&&h1!=h2)ans=min(ans,a);
	h1=h[1],h2=min(h[0],h[2]),a=0;
	if(d>0){ 
	if(h[0]==h[2]){m=nextpos(h2,h[0]);h2=max(0,h2-d*m);a+=m;}
	if(h1>=h2){m=nextpos(h1,h2);h1=max(0,h1-d*m);a+=m;}
    }
	if(h1>=0&&h1!=h2)ans=min(ans,a);
	if(ans==inf)ans=-1;
	printf("%d\n",ans);
	return 0;
}