#include <bits/stdc++.h>
#include <typeinfo>
#include<iostream>

using namespace std;
#define pb push_back
#define se second
#define fi first
#define FOR(i,n) for(int j=i;j<n;j++)
#define mp make_pair
#define ll long long

/*long long int red  = 0, black = 0 , adds = 0 ,rp=0 ,bp=0,reds=0,blacks=0,ans=0,y;
void dfs(int i, int* visited,vector< pair <int,int> > graph [],vector<int>& c,int z)
{
    if(visited[i]==1)
        return ;
    visited[i]=1;
    for(int j = 0 ; j < graph[i].size();j++)
    {
        if(visited[graph[i][j].first]==0)
        {
          if(c[graph[i][j].first]==0 && c[i]==0)
          {
              if(z>0&&z<=y)
              {
                  if(c[z]==1)
                  {
                      int b;
                      for(b = 0 ; b <graph[z].size();b++)
                      {
                          if(graph[z][b].first==i)
                            break;
                      }
                      ans += graph[z][b].second*blacks;
                  }

              }
                red += graph[i][j].second;
              //rp++;
          }
          else if((c[graph[i][j].first]==1 && c[i]==0)||(c[graph[i][j].first]==0 && c[i]==1))
          {
              black+=graph[i][j].second;
          }
          else
          {
              if(z>0&&z<=y)
                 {
                     if(c[z]==0){
                        int b;
                      for(b = 0 ; b <graph[z].size();b++)
                      {
                          if(graph[z][b].first==i)
                            break;
                      }
                       ans += graph[z][b].second*reds;
                     }

              }
                adds += graph[i][j].second;
              //bp++;
          }
          dfs(graph[i][j].first,visited,graph,c,i);
        }
    }
}
int main() {
    int n;
    cin >> n;
    vector<int> c(n+1);
    for(int c_i = 1; c_i <= n; c_i++){
       cin >> c[c_i];
        if(c[c_i]==0)
            reds++;
        else
            blacks++;
    }
    y=n;
    ans = 0;
    pair <int,int> a,b;
    vector< pair <int,int> > graph[n+1];
    for(int a0 = 0; a0 < n-1; a0++){
        int u;
        int v;
        int w;
        cin >> u >> v >> w;

        a.first = u ;
        a.second = w ;
        b.first = v;
        b.second = w;
        graph[u].pb(b);
        graph[v].pb(a);
    }
    /*for(int i = 1; i<=n ;i++)
    {
        cout << i << "---->";
        for(int j = 0 ; j < graph[i].size() ;j++)
        {
            cout << graph[i][j].first << " " <<graph[i][j].second << "\t";
        }
        cout << "\n";
    }
    int* visited = (int *)calloc(n+1,sizeof(int));
    for(int i = 1 ;i<=n;i++)
    {
        if(c[i]==0)
        {
            dfs(i,visited,graph,c,0);
            break;
        }
    }
    //dfs(1,visited,graph,c);
    //cout << red << "  "<< black << endl;
    long long int x = red*blacks + (black+adds)*(reds) + ans;
    cout << x << endl;
    return 0;
}*/
const int maxn = 1600;
const int mod = 1e9+7;

int main() {
    int p,d,m,s;
    cin >> p >> d>>m>>s;
    int ans = 0;
    while(s>=0)
    {
        if(p-ans*d >= m){
        if(s-(p-ans*d)>=0)
        {
            s -= (p-ans*d);
            ans++;
        }
        else
            break;
        }
        else
        {
           if(s-m>=0)
            {
                ans++;
                s-=m;
            }
            else
                break;
        }
    }
    cout << ans;
}