#include <iostream>
#include <vector>
#define rep(i, n) for (int i = 0; i < n; i++)
using namespace std;

int main() {
    int n, m, p, q;
    cin >> n >> m >> p >> q;
    p--;                        // 1-based to 0-based
    vector<int> month(12, m);
    rep(i, q) month[p + i] *= 2;
    int i;
    for (i = 0; n > 0; i++) n -= month[i % 12];
    cout << i << endl;
    return 0;
}