#include <bits/stdc++.h>

using namespace std;

int main() {
    int p;
    int d;
    int m;
    int s;
    cin >> p >> d >> m >> s;
    int cnt=0,sum=0;
    while(1){
        if(sum>s){
            break;
        }
        if(p>m){
            sum+=p;
            p = p-d;
        }
        else{
            sum+=m;
        }
        cnt++;
    }
    
    cout << cnt-1 << endl;
    return 0;
}