#include<bits/stdc++.h>
using namespace std;
int main()
{
    int p,d,m,s;
    cin>>p>>d>>m>>s;
    int i=0,a[1000000]={0};
    while(p>=m)
    {
       
        a[i]=p;
        p=p-d;
        i++;
    }
    int j;
    for(j=i;j<1000000;j++)
    {
        a[j]=m;
    }
    int count=0;
    i=0;
    while(s>=0)
    {
        s=s-a[i];
        count++;
        i++;
    }
    cout<<(count-1)<<endl;
    return 0;
}