#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
//#include<cctype>
#include<climits>
#include<iostream>
#include<string>
#include<vector>
#include<map>
//#include<list>
#include<queue>
#include<deque>
#include<algorithm>
//#include<numeric>
#include<utility>
#include<complex>
//#include<memory>
#include<functional>
#include<cassert>
#include<set>
#include<stack>

const int dx[] = {1, 0, -1, 0};
const int dy[] = {0, 1, 0, -1};
using namespace std;
typedef long long ll;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef pair<int, int> pii;

int H[3];
const ll INF = 1ll<<55;

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    int d;
    cin >> d;
    for (int i = 0; i < 3; i++) cin >> H[i];
    if (d == 0) {
        bool yes = false;
        if (H[0] > H[1] && H[1] < H[2] && H[0] != H[2]) yes = true;
        else if (H[0] < H[1] && H[1] > H[2] && H[0] != H[2]) yes = true;
        if (yes) cout << 0 << endl;
        else cout << -1 << endl;
        return 0;
    }
    ll ans = INF;
    // 真ん中が一番低い
    {
        ll sum = 0;
        vector<int> nH(3);
        for (int i = 0; i < 3; i++) nH[i] = H[i];
        if (H[0] == H[2]) {
            nH[0] = max(0, nH[0]-d);
            sum++;
        }
        if (nH[0] > nH[2]) swap(nH[0], nH[2]);
        if (nH[0] != 0) {
            int diff = nH[1] - nH[0];
            if (diff >= 0) {
                int num = diff/d;
                nH[1] -= d*num;
                if (nH[1] >= nH[0]) {
                    num++;
                }
                sum += num;
            }
            ans = min(ans, sum);
        }
    }
    // 真ん中が一番高い
    {
        ll sum = 0;
        vector<int> nH(3);
        for (int i = 0; i < 3; i++) nH[i] = H[i];
        {
            int diff = nH[0]-nH[1];
            if (diff >= 0) {
                int num = diff/d;
                nH[0] -= num*d;
                if (nH[0]-nH[1] >= 0) {
                    nH[0] -= d;
                    nH[0] = max(0, nH[0]);
                    num++;
                }
                sum += num;
            }
        }
        {
            int diff = nH[2]-nH[1];
            if (diff >= 0) {
                int num = diff/d;
                nH[2] -= num*d;
                if (nH[2]-nH[1] >= 0) {
                    nH[2] -= d;
                    nH[2] = max(0, nH[2]);
                    num++;
                }
                sum += num;
            }
        }
        if (nH[0] == nH[2]) {
            if (nH[0] != 0) {
                sum++;
                ans = min(ans, sum);
            }
        } else {
            ans = min(ans, sum);
        }
    }
    if (ans == INF) ans = -1;
    cout << ans << endl;
    return 0;
}