#include <bits/stdc++.h>

using namespace std;

int howManyGames(int p, int d, int m, int s) {
   int k=p,c=0,sum=0;
    while(1)
    {
        if((sum+k)>s)
            break;
        sum=sum+k;
        if((k-d)>m)
        k=k-d;
        else
            k=m;
        c++; 
    }
    return c;
}

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;
}