#include <bits/stdc++.h>

using namespace std;

int howManyGames(int p, int d, int m, int s) {
    // Return the number of games you can buy
    int games=0,total=0;
    if(p<m){
        p=m;
    }
    s=s-p;
    while(s>=0){
        games++;
        p=p-d;
        if(p<=m){
        p=m;
        }
        s=s-p;
    }
    /*for(;;){
        total+=p;
        if(total>s){
            //games--;
            break;
        }else{
            games++;
        }
        if(p>m){
            p=p-d;
        }else{
            p=m;
        }
    }*/
    return games;
    }

int main() {
    int p;
    int d;
    int m;
    int s;
    cin >> p >> d >> m >> s;
    int answer = howManyGames(p, d, m, s);
    cout << answer << endl;
    return 0;
}