#include <bits/stdc++.h>

using namespace std;
int main()
{
    int p,d,m,s;
    cin>>p>>d>>m>>s;
    int c1=0,c2=0,sum=0;
    while(sum<=s)
    {
        if(p>=m)
        {
        sum+=p;
        p-=d;
        }
        else sum+=m;
        c1++;      
    }
    if(sum>s)
    cout<<c1-1<<endl;
    else
        cout<<c1<<endl;
}