#include <bits/stdc++.h>

using namespace std;

int howManyGames(int p, int d, int m, int s) {
    // Return the number of games you can buy
    int i=p,s1=0,c=0;
    while(s1<=s){
        s1=s1+i;
        if(i-d>m)
        i=i-d;
        else
        i=m;
        c++;
    }
    return c-1;
}

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;
}