#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;


int main() {
    int a,b,c,d;
    cin>>a>>b>>c>>d;
    int cc=0,i=0;
    while(d){
        if(a-i*b>c)
          d-=(a)-(i*b);
        else
          d-=c;
        if(d<0)
            break;
        else{
            cc++;
            i++;
        }
        
    }
    cout<<cc<<"\n";
    return 0;
}