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


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