#include <bits/stdc++.h>
#define inf 0x3f3f3f3f
#define MOD 1000000007
#define MODL 1000000000000000003
#define pb push_back
#define ll long long int
#define llu long long unsigned int
#define vi vector<int>
#define vii vector<pair<int,int> >
#define pii pair<int,int>
#define mp make_pair
#define ms(x, v) memset(x, v, sizeof x)
#define fr(i, a, b) for(int i=a; i<=b; i++)
#define fb(i, a, b) for(int i=a; i>=b; i--)
#define ft first
#define sd second
 
using namespace std;
 
#define err(x) cout<<#x"="<<x<<endl
#define err2(x,y) cout<<#x"="<<x<<" "#y"="<<y<<endl
#define err3(x,y,z) cout<<#x"="<<x<<" "#y"="<<y<<" "#z"="<<z<<endl

const int maxn= 200001;

int main()
{    
    //freopen("in.txt","r",stdin);//freopen("out1.txt","w",stdout);
    //ios::sync_with_stdio(false);cin.tie(0);
    int p,d,m,s,buy=0,cost;cin>>p>>d>>m>>s;
    if(p>s)cout<<0;
    else
    {
        cost=p;
        buy=1;
        s-=p;
        while(1)
        {
            if(cost>m+d)
                cost-=d;
            else cost=m;
            if(s<cost)break;
            buy++;
            s-=cost;
        }
        cout<<buy;
        
    }
    return 0;
}