#include <bits/stdc++.h>

using namespace std;

int howManyGames(int p, int d, int m, int s) {
    int cnt=0;
    int i=p;
    while (s>=i) {
        //printf("%d\n",i);
        cnt+=1;
        s-=i;
        if (i>m) i-=d;
        if (i<m) i=m;
    }
    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;
}