#include <bits/stdc++.h>

using namespace std;

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

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;
}