#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef pair<int,int> pii;

int s;
int p,d,m;

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