#include <bits/stdc++.h>

using namespace std;

int howManyGames(int p, int d, int m, int s) {
    int count=0,curp=p,curs=s;
    
    
    while(curs>0)
    {
        curs-=curp;
        if(curs<0)
            break;
        count++;
        if(curp-d>=m)
            curp-=d;
        else
            curp=m;
    }
    return count; 
    // Return the number of games you can buy
}

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;
}