#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;


int main() {
    int p,d,m,s,i,j,t=0;
    cin>>p>>d>>m>>s;
    t=p;
    p=p-d;
    i++;
    while(t<s)
    { while(t<s && p>m)
      { t=t+p;
        p=p-d;
      i++;}
       while(t<s)
       { t=t+m;
       i++;}
    }
    if(t>s)
        i=i-1;
    cout<<i;
    
    
    return 0;
}