#include <bits/stdc++.h>

using namespace std;

const int INF = numeric_limits<int>::max();
int d;

void magic(int& n) {
  n -= d;
  if (n < 0) n = 0;
}

bool isKadomatsu(int h1, int h2, int h3) {
  return h1 != h2 && h1 != h3 && h2 != h3 && ((h2 > h1 && h2 > h3) || (h2 < h1 && h2 < h3));
}

int solve1(int h1, int h2, int h3) {
  if (h2 == 0) return INF;
  int res = 0;
  while (h1 >= h2) {
    magic(h1);
    ++res;
  }
  while (h3 >= h2) {
    magic(h3);
    ++res;
  }
  if (h1 == h3) {
    magic(h1);
    ++res;
  }
  if (h1 == h3) return INF;
  return res;
}

int solve2(int h1, int h2, int h3) {
  int res = 0;
  if (h1 == h3) {
    magic(h1);
    ++res;
  }
  if (h1 == 0 || h3 == 0) return INF;
  while (min(h1, h3) <= h2) {
    magic(h2);
    ++res;
  }
  return res;
}

int main() {
  int h1, h2, h3;
  cin >> d >> h1 >> h2 >> h3;
  if (isKadomatsu(h1, h2, h3)) {
    cout << 0 << endl;
  } else if (d == 0) {
    cout << -1 << endl;
  } else {
    int res = min(solve1(h1, h2, h3), solve2(h1, h2, h3));
    cout << (res == INF ? -1 : res) << endl;
  }
}