#include <bits/stdc++.h>

using namespace std;

int howManyGames(int p, int d, int m, int s) {
    int count=0,i;
    long sum=0;
    if(s<p)
        return 0;
    else
    {
        for(i=0;sum<s;i++)
        {
            if(i==0)
                sum=p;
            else
            {
                if(p-d<=m)
                    p=m;
                else
                    p=p-d;
                sum+=p;
            }
            if(sum<=s)
                count++;
        }
    }
    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;
}