#include <bits/stdc++.h>
using namespace std;


int main() {
    int p,d,m,s,mp1,mp2=0;
    cin>>p>>d>>m>>s;
    mp1=p;
    while(mp1<=s){
        if(p-d>m){
            p=p-d;
            mp1=mp1+p;
            mp2++;
        }
        else {
            p=m;
            mp1=mp1+p;
            mp2++;
        }
    }
    cout<<mp2<<endl;
    return 0;
}