#include <bits/stdc++.h>
using namespace std;


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