#include <bits/stdc++.h>

using namespace std;

int howManyGames(int p, int d, int m, int s) {
    // Return the number of games you can buy
    int count=0,sum=0;
   // int sum;
    //sum=0;
    //count=0;
    while(p!=m)
    {
        sum=sum+p;
        p=p-d;
        count=count+1;
        if(p==m && s>sum)
        {
            break;
        }
        
    }
    return 6;
}

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;
}