#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 */   
    long long int p , d , m ,s , sum=0 , cnt=0;
    cin >> p >> d >> m >>s;
    for(int i=p;i>=m;i-=d){
        if(sum+i <= s) {
            sum = sum + i;
        cnt++;
        }
        else 
        {
            cout << cnt << "\n";
            return 0;
        }
    }
    while(sum+m <= s){
        sum = sum + m;
        cnt++;
    }
    cout << cnt << "\n";
    return 0;
}