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


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