#include <bits/stdc++.h>

using namespace std;

int howManyGames(int p, int d, int m, int s) 
{
    int count=0;
    s = s-p;
    count++;
    p = p-d;
    while(1)
    {
        if(s<m)
        {
            return count;
        }
        else
        {
            if(p<=d)
            {
                s = s-d;
                count++;    
            }
            s = s-p;
            count++;
            p = p -d;
        }   
            
    }
    
}

int main() {
    int p;
    int d;
    int m;
    int s;
    cin >> p >> d >> m >> s;
    int answer = howManyGames(p, d, m, s);
    cout << answer << endl;
    return 0;
}