/*
 * If you're not willing to make sacrifices yourself, you'll never be
 * able to change anything. In order to overcome monsters, you must
 * be willing to abandon your own humanity.
 * ~ Arlert
 */

#include <bits/stdc++.h>

using namespace std;

typedef pair<int, int> II;
typedef vector<II> VII;
typedef vector<int> VI;
typedef vector<VI> VVI;

typedef long long int LL;

#define PB push_back
#define MP make_pair
#define F first
#define S second
#define SZ(a) (int)(a.size())
#define ALL(a) a.begin(), a.end()
#define SET(a, b) memset(a, b, sizeof(a))
#define si(n) scanf("%d", &n)
#define dout(n) printf("%d\n", n)
#define sll(n) scanf("%lld", &n)
#define lldout(n) printf("%lld\n", n)

#define TRACE

#ifdef TRACE
#define trace(...) __f(#__VA_ARGS__, __VA_ARGS__)
template <typename Arg1>
void __f(const char *name, Arg1 &&arg1) {
  cerr << name << " : " << arg1 << std::endl;
}
template <typename Arg1, typename... Args>
void __f(const char *names, Arg1 &&arg1, Args &&... args) {
  const char *comma = strchr(names + 1, ',');
  cerr.write(names, comma - names) << " : " << arg1 << " | ";
  __f(comma + 1, args...);
}
#else
#define trace(...)
#endif

#define fast_io                     \
  ios_base::sync_with_stdio(false); \
  cin.tie(NULL)

#define endl '\n'

int main() {
  fast_io;
  int p, d, m, s;
  cin >> p >> d >> m >> s;
  int tot = 0;
  while (s >= p) {
    tot++;
    s -= p;
    p = max(p - d, m);
  }
  cout << tot << endl;
  return 0;
}