#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 sum=p;
    int cnt=0;
    if(sum<=s)
        cnt++;
    while(1){
        if(p-d>m){
            p=p-d;
            sum+=p;
        }
        else{
            p=m;
            sum+=p;
        }
        if(s>=sum)
            cnt++;
        else
            break;
    }
    return cnt;
}

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;
}