#include <iostream>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <string>
#include <iomanip>
#include <algorithm>
#include <cmath>
#include <stdio.h>
using namespace std;
#define int long long
int MOD = 1000000007;
signed main() {
	cin.tie(0);
	ios::sync_with_stdio(false);
	int N, M, P, Q;
	cin >> N >> M >> P >> Q;
	P--;
	int res = 0;
	while(N>0){
		
		N -= M;
		if (P <= (res % 12) && (res % 12) < P+Q) {
			N -= M;
		}
		res++;
		//cerr << N << endl;
	}
	cout << res << endl;
}