#include <bits/stdc++.h>

using namespace std;

int howManyGames(int p, int d, int m, int s) {
    int num=0,cost=0;
    while(cost<s){
        cost+=p;
       if(p!=m){
           if(p-d>=m)p-=d;
           else{
               p=m;
           }
       }
        if(cost>s)break;
        num++;
    }
    return num;
}

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;
}