#include <bits/stdc++.h>

using namespace std;
typedef long long ll;


int main(){
    int n, m, p, q, ans, y;
    cin >> n >> m >> p >> q;
    y = (12+q)*m;
    ans += 12*(n/y);
    n %= y;
    for (int i = 1; i <= 12; i++){
        ans++;
        n -= m;
        if (p <= i && i <= p+q-1)
            n -= m;
        if (n <= 0)
            break;
    }
    
    cout << ans << endl;
    return 0;

}