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


int main() {
    int p,d,m,s;
    cin>>p>>d>>m>>s;
    int spent=p;
    int count=1;
    int prev=p;
    while(spent<=s){
        
        if((p-d)>m){
           
        spent+=(p-d);
        p=p-d;}
        else {
           
            spent+=m;
        p=m;}
        
        count++;
        
    }
    if(spent == s)
        cout<<count<<endl;
    else cout<<count-1<<endl;
   // cout<<count<<endl;
    
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    return 0;
}