#include<bits/stdc++.h>
#define ll long long int
#define el "\n"
#define fio ios_base::sync_with_stdio(false),cin.tie(NULL)
#define ull unsigned long long int
#define ld long double
const long double PI = atan(1.0)*4.0;
const ll MOD = 1e9+7;
const ll INF = 1e18;
using namespace std;
bool isprime(ll n)
{
    for(ll i=2;i*i<=n;i++)
    {
        if(n%i==0)
            return false;
    }
    return true;
}
int main()
{
    fio;
    ll p,d,m,s,sm=0,cnt=0;
    cin>>p>>d>>m>>s;
    ll a[10005]={0};
    for(ll i=0;i<10005 && sm<=s;i++)
    {
        a[i]=p-i*d;
        if(a[i]<m)
        {
            a[i]=m;
        }
        sm=sm+a[i];
        cnt++;
        
    }
    cout<<cnt-1;
}