#include <bits/stdc++.h>

using namespace std;

int howManyGames(int p, int d, int m, int s) {
    int cnt=0;
    int prev=p+d,cur;
    while(1)
    {
        cur=prev-d;
        if(cur<m)
            cur=m;
        
        if(s<cur)
           break;
        s-=cur;
        cnt++;
        prev=cur;
    }
    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;
}