#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i, s, e) for (int i = (int)s; i < (int)e; i++)

int main() {
    cin.tie(nullptr);
    
    int N, M, P, Q;
    cin >> N >> M >> P >> Q;
    
    int y = M * 12 + Q * M;
    int ans = (N / y) * 12;
    N %= y;
    
    rep(i, 1, 13) {
        if (P <= i && i <= P + Q - 1) N -= 2 * M;
        else N -= M;
        
        if (N <= 0) {
            cout << i + ans << '\n';
            return 0;
        }
    }
}