#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;


int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */  
    int p,d,m,s;
    cin>>p>>d>>m>>s;
    int count =0;
    int x = s-p;
    p = p-d;
    if(x>=0)
    {
      count++;
    while(p>m)
    {
        
        x = x-p;
        if(x>=0)
        {
            count++;
            //x = x-p;
        }
        else
        {
            break;
        }
        p = p-d;
    }
    
    while(x>0)
    {
        x = x-m;
        if(x>=0)
        {
           count++;
           //x = x-m;
        }
        else
            break;
        
    }
    }
    
    cout<<count;
    return 0;
}