#include <bits/stdc++.h>

using namespace std;

int howManyGames(int p, int d, int m, int s) {
    if(p>s)
        return 0;
    int i=0;
    int count=0,c;
    c=max(p, m);
    while(s-c>=0){
        s-=c;
        ++count;
        ++i;
        c=max(c-d, m);
        
        
    }
    return count;
}

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;
}