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


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