#include <bits/stdc++.h>

using namespace std;

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

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;
}