#include <bits/stdc++.h>

using namespace std;


int main() {
    long int p,d,m,s,sum=0,x,count=0;
    cin >> p >> d >> m >> s;
    x = p;
    long int answer;
    for (;;)
    {
        sum += x;    
        if (x-d>m){
            x=x-d;
        }
        else{
            x=m;
        }
        if (sum<=s){
            count++;
        }
        else{
            break;
        }
    }
    answer= count;
    cout << answer << endl;
    return 0;
}