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


int main() {
    int i,j,n,p,d,m,s;
    int sum=0,count=0;
    cin>>p>>d>>m>>s;
    do
    {
     sum=sum+p;
     if(p-d>=m)   
     p=p-d;
     else
     p=m;   
     count++;   
    }while(sum<=s);
    cout<<count-1;    
    return 0;
}