#include <iostream>
#include <sstream>
#include <cstdio>
#include <cmath>
#include <cstring>
#include <cctype>
#include <string>
#include <vector>
#include <list>
#include <set>
#include <map>
#include <queue>
#include <stack>
#include <algorithm>
#include <functional>
#include <iomanip>
#define cin(a) cin>>a
#define IOS ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define cout(a) cout<<a
#define nl cout<<'\n'
#define ff first
#define ss second
#define READ freopen("input.txt","r",stdin);
#define WRITE    freopen("output.txt","w",stdout);
#define fill(a,x) memset(a,x,sizeof(a));
#define loop(i,x,n) for(int i=x;i<n;i++)
#define loopr(i,x,n) for(int i=n;i>=x;i--)
#define TC() ll t;cin>>t;while(t--)
#define ll long long
#define mod 1000000007
#define N 100020
#define vi vector<ll>
#define vs vector<string>
#define pii pair<ll,ll>
#define vpi vector<pair<ll,ll> >
#define mii map<ll,ll>
#define msi map<string,ll>
#define mis map<ll,string>
#define si set<ll>
#define pb push_back
#define mp make_pair
#define sort(x) sort(x.begin(),x.end())
#define reverse(x) reverse(x.begin(),x.end())
#define all(a)         a.begin(), a.end()
#define ull unsigned long long
#define two(x) (1<<x)
#define inf 1<<28
#define debug1(x) cout << #x << ": " << x <<'\n'
#define debug2(x, y) cout << #x << ": " << x << '\t' << #y << ": " << y <<'\n'
#define debug3(x, y, z) cout << #x << ": " << x << '\t' << #y << ": " << y << '\t' << #z << ": " << z <<'\n'
using namespace std;
ll dx[]={1,0,-1,0};ll dy[]={0,1,0,-1}; //4 Direction
//ll dx[]={1,1,0,-1,-1,-1,0,1};int dy[]={0,1,1,1,0,-1,-1,-1};//8 direction
ll gcd(ll x,ll y)
{
    if(y==0)
        return x;
    else
        return gcd(y,x%y);
}
ll expo(ll n,ll m)   //MODULAR EXPONENTIATION
{
    ll r=1;
    while(m>0)
    {
        if(m%2)
            r=(r*n)%mod;
        n=(n*n)%mod;
        m=m/2;
    }
    return r%mod;
}
int main()
{

   IOS;
   /*#ifndef ONLINE_JUDGE
   freopen("input.txt","r",stdin); 
   freopen("output.txt","w",stdout);
   #endif*/
   /********************* Code starts here ************************/
   ll p,d,m,s;
   cin>>p>>d>>m>>s;
   ll ans=0;
   while(s>=p)
   {
    if(s<=0)
      break;
    if(p<=s)
      ans++,s-=p;
    p-=d;
    if(p<=m)
      p=m;
   }
   cout<<ans;
   return 0;
}