#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;
#define ll long long int

int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */  
    ll a,b,c,d,i=0,sum=0;  cin>>a>>b>>c>>d;
    while(1)
    {
        sum+=a;
        if(a-b>c)  {a-=b;}
        else       {a=c;}
        if(sum>d)   {break;}
        i++;
    }
    cout<<i<<endl;
    return 0;
}