#include <bits/stdc++.h>

using namespace std;

int howManyGames(int p, int d, int m, int s) {
    // Return the number of games you can buy
  
    int c=1, sum =0, flag=1;
    
    if(p>s)
      return 0;
    if(p<=s)
      sum=p;
  
    if(p-d>m){
      p=p-d;
      flag=1;
    }
    else{
      flag=0;
      p=m;
    }
  
    
    while(sum+p<=s){
      
      //cout<<p<<endl;
      
      c++;
      
      if(flag==1){
        
        sum+=p;
      }
      else
        sum+=m;
      
      if(p-d>m){
        p=p-d;
        flag=1;
      }
      else{
        flag=0;
        p=m;
      }
      
    }
  
  //cout<<"sum = "<<sum<<endl;
  
  return c;
}

int main() {
    int p;
    int d;
    int m;
    int s;
    cin >> p >> d >> m >> s;
    int answer = howManyGames(p, d, m, s);
    cout << answer << endl;
    return 0;
}