#include <string>
#include <vector>
#include <algorithm>
#include <numeric>
#include <set>
#include <map>
#include <queue>
#include <iostream>
#include <sstream>
#include <cstdio>
#include <cmath>
#include <ctime>
#include <cstring>
#include <cctype>
#include <cassert>
#include <limits>
#include <functional>
#define rep(i,n) for(int (i)=0;(i)<(int)(n);++(i))
#define rer(i,l,u) for(int (i)=(int)(l);(i)<=(int)(u);++(i))
#define reu(i,l,u) for(int (i)=(int)(l);(i)<(int)(u);++(i))
#if defined(_MSC_VER) || __cplusplus > 199711L
#define aut(r,v) auto r = (v)
#else
#define aut(r,v) __typeof(v) r = (v)
#endif
#define each(it,o) for(aut(it, (o).begin()); it != (o).end(); ++ it)
#define all(o) (o).begin(), (o).end()
#define pb(x) push_back(x)
#define mp(x,y) make_pair((x),(y))
#define mset(m,v) memset(m,v,sizeof(m))
#define INF 0x3f3f3f3f
#define INFL 0x3f3f3f3f3f3f3f3fLL
using namespace std;
typedef vector<int> vi; typedef pair<int,int> pii; typedef vector<pair<int,int> > vpii; typedef long long ll;
template<typename T, typename U> inline void amin(T &x, U y) { if(y < x) x = y; }
template<typename T, typename U> inline void amax(T &x, U y) { if(x < y) x = y; }

int main() {
	int d, H[3];
	while(cin >> d >> H[0] >> H[1] >> H[2]) {
		int ans = 0;
		if(H[0] == H[2]) {
			++ ans;
			H[0] = max(H[0] - d, 0);
		}
		if(H[0] > H[2]) swap(H[0], H[2]);
		if(d == 0) {
			ans = H[0] != H[2] && (H[2] < H[1] || H[0] > H[1]) ? 0 : INF;
		}else {
			if(H[0] == H[2]) ans = INF;
			int x = H[0] == 0 ? INF : max(0, H[1] - H[0] + d) / d;
			int y = H[0] >= H[1] ? INF : max(0, H[2] - H[1] + d) / d;
			if(y != INF && max(0, H[2] - d * y) == H[0]) {
				if(H[0] == 0)
					y = INF;
				else
					++ y;
			}
			ans += min(x, y);
		}
		if(ans >= INF)
			puts("-1");
		else
			cout << ans << endl;
	}
	return 0;
}