#include <bits/stdc++.h>

using namespace std;

int howManyGames(int p, int d, int m, int s) {
    int r=0,x=0;
    int count=0;
    while(1)
    {
        r+=p;
        if(x==0)
        p=p-d;
        if(p<=m){
            x=1;
            p=m;
        }
        if(r<=s)
            count++;
        else
            return count;
    }
    // Return the number of games you can buy
}

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;
}