#include <bits/stdc++.h>
using namespace std;

int main(){
    int n, m, p, q;
    cin >> n >> m >> p >> q;
    int ans = 0;
    while(n > 0){
        ans++;
        if(p-1 <= ans%12 && ans%12 < p+q-1) n -= 2*m;
        else n -= m;
    }
    cout << ans << endl;
    return 0;
}