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


int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */
    lli p,d,m,s,i;
    cin>>p>>d>>m>>s;
    for(i=0;;i++){
        if(s-p<0)
            break;
        else{
            s=s-p;
            if(p-d<=m)
                p=m;
            else
                p=p-d;
        }
    }
    cout<<i<<endl;
    return 0;
}