#include <bits/stdc++.h>

using namespace std;
int p, d, m, s;

int main() {
    scanf("%d%d%d%d", &p, &d, &m, &s);
    int count = 0;
    while (s > 0)
    {
        if (s-p < 0)
        {
            break;
        }
        s -= p;
        if (p - d < m)
            p = m;
        else
            p -= d;
        count++;
    }
    printf("%d", count);
    return 0;
}