/*
What..??                 ?
        __________      ?
       |          |    ?
       |          |
      _|   m   m  |_
       |     H    |
        \   ___  /
         |   ~  |
Why.......?
Seriously.....!
Why are you answering..??
Okay.why not?
*/
#include <bits/stdc++.h>
using namespace std;
#define sf1(a)             scanf("%d",&a)
#define sf2(a,b)           scanf("%d%d",&a,&b);
#define sfl1(a)            scanf("%lld",&a)
#define sfl2(a,b)          scanf("%lld%lld",&a,&b)
#define hi                 printf("here!\n")
#define                    endl '\n'
#define fs                 first
#define sc                 second
#define pb                 push_back
#define sz(a)              int ((a).size())
#define all(a)             a.begin(),a.end()
#define inf                (1 << 30)
#define mx                 100009
#define FO(i,a,b)          for(int i=int(a)-(a>b);i!=(b)-(a>b);i+=1-2*(a>b))
#define CLR(x)             memset(x,0,sizeof(x))
#define nl                 printf("\n");
#define R                  return 0
#define ll                 long long
typedef pair<int,int>      ii;
typedef vector <int>       vec;
typedef map<int,int>       mapp;

int main()
{
   int c,n,d,s;
   cin >> c >> n >> d >> s;
   int sum = 0;
   int cnt = 0;
   while(sum < s){
    sum += c;
    if(c - n >= d) c -= n;
    else{
        c = d;
    }
    if(sum <= s) cnt++;
   }
   cout << cnt << endl;
   R;
}
/*

*/