#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <cstdio>
#include <cstring>
#include <cmath>
using namespace std;
using ll = long long;

int main() {
    int n, m, p, q;
    cin >> n >> m >> p >> q;
    p--;

    int a[12];
    for (int i = 0; i < 12; i++) {
        a[i] = m;
    }
    for (int i = p; i < p + q; i++) {
        a[i] *= 2;
    }

    for (int k = 0;; k++) {
        int i = k % 12;
        n -= a[i];
        if (n <= 0) {
            cout << k + 1 << endl;
            exit(0);
        }
    }

    return 0;
}