#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;
    
    if(s > p ){
        s-=p;
        if(s>=0) 
            count++;
        while(s>0){
            if(p-d > m){
                s-=(p-d);
                p-=d;
                if(s>=0)
                count++;
            }else{
                s-=m;
                if(s>=0) count++;
            }
        }
    }
    
    cout<<count<<endl;
    return 0;
}