#include <bits/stdc++.h>

using namespace std;

int howManyGames(int p, int d, int m, int s) {
    if(s<p)
        return 0;
    int curr=p;
    int count=0;
    while(curr>m){
        if(s>curr)
            count+=1;
        s=s-curr;
        curr=curr-d;
    }
    while(s-m>=0){
        s=s-m;
        count+=1;
    }
    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;
}