#include <algorithm>
#include <vector>
#include <cfloat>
#include <string>
#include <cmath>
#include <set>
#include <cstdlib>
#include <map>
#include <ctime>
#include <iomanip>
#include <functional>
#include <deque>
#include <iostream>
#include <cstring>
#include <queue>
#include <cstdio>
#include <stack>
#include <climits>
#include <sys/time.h>
#include <cctype>

using namespace std;

typedef long long ll;

int main() {
  ll d;
  cin >> d;
  ll a, b, c;
  cin >> a >> b >> c;
  if ((a < b && b > c) || (a > b && b < c)) {
    puts("0");
  }else if (b == 0 || d == 0) {
    puts("-1");
  }else {
    ll ans = 0;
    if (b <= a) {
      ans += (a-b)/d+1;
    }
    if (b <= c) {
      ans += (c-b)/d+1;
    }
    ans = min(ans, (b-min(a, c))/d+1);
    std::cout << ans << std::endl;
  }
}