#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 a=0,cnt=0;
    a=a+p;
    while(a<=s){
      
        p=p-d;
    if(p<=m){
        a=a+m;
    }else{
   a=a+p;
    }
        cnt++;
    }
    return cnt;
        
    }
    
    


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;
}