/* # # # _realRPG_ # # # */

#include "bits/stdc++.h"

#define ll long long
#define ull unsigned long long

#define vi  vector <int>
#define vs  vector <string>
#define vll  vector <long long>
#define vpii vector <pair <int, int> >
#define vpss vector <pair <string, string> >
#define vpll vector <pair <long long, long long> >
#define pii pair <int,int>
#define pll pair <long long, long long>
#define pss pair <string, string>

#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()

#define fi(i,a,b,c) for(int i=a; i<b; i+=c)
#define fl(i,a,b,c) for(long long i=a; i<b; i+=c)
#define rfi(i,a,b,c) for(int i=a; i>=b; i-=c)
#define rfl(i,a,b,c) for(long long i=a; i>=b; i-=c)

#define pb  push_back
#define mk  make_pair
#define ep  emplace_back
#define F first
#define S second
#define sc scanf
#define pr printf

using namespace std;

const int md = 1e9 + 7;
const int MAX = 1e5 + 5;
const int MAXN = 1e6 + 5;

inline int fsc() {
        int ip = getchar(), ret = 0, flag = 1;
        for (; ip<'0' || ip>'9'; ip = getchar_unlocked())
                if (ip == '-') {
                        flag = -1; ip = getchar_unlocked();
                        break;
                }
        for (; ip >= '0'&&ip <= '9'; ip = getchar_unlocked())
                ret = ret * 10 + ip - '0';
        return flag*ret;
}

/*class {
    public:
};*/

void solve() {
      int a,b,c,d;
      cin>>a>>b>>c>>d;
      int ans=0,ct=0;
      int flag=0;
      while(ans<=d) {
            if(flag==1) {
                  ans+=c;
                  if(ans<=d) ct++;
            } else {
                  if(a-b<=c) {
                        flag=1;
                        ans+=a;
                        if(ans<=d) ct++;
                  } else{
                        ans+=a;
                        if(ans<=d) ct++;
                        a=a-b;
                  }
            }
      } cout<<ct;
} int main(){ ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL); solve(); return 0; }