#include <bits/stdc++.h>

using namespace std;

int howManyGames(int p, int d, int m, int s) {
    
    int i=p,sum=0,count=0;
    while(sum <=s)
    {
        sum+=i;
        //cout<<i<<" ";
        if(i-d<=m)i=m;
        else i=i-d;
        
        if(sum<=s)count++;
        //cout<<i<<" ";
    }
    return count;
}

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;
}